Edit in JSFiddle

<div id="nav">
    <div id="wood">
        <a onclick="render(wood)">Woodworking</a>
    </div>
    <div id="metal">
        <a onclick="render(metal)">Metalworking</a>
    </div>
    <div id="cnc">
        <a onclick="render(cnc)">CNC</a>
    </div>
    <div id="print">
        <a onclick="render(print)">3D Printing</a>
    </div>
    <div id="draft">
        <a onclick="render(draft)">Drafting</a>
    </div>
    <div id="weld">
        <a onclick="render(weld)">Welding</a>
    </div>
    <div id="sand">
        <a onclick="render(sand)">Sand Blast</a>
    </div>
    <div id="finishing">
        <a onclick="render(finishing)">Finishing</a>
    </div>
    <div id="laser">
        <a onclick="render(laser)">Laser Cutting</a>
    </div>
    <div id="all">
        <a onclick="render(all)">All</a>
    </div>
</div>

var all = [
{source: "Tockwotton", target: "List", type: "woodworking"},
{source: "Tockwotton", target: "Prince Lab", type: "woodworking"},
{source: "Prince Lab", target: "Prince Lab", type: "metalworking"},
{source: "Tockwotton", target: "List", type: "cnc"},
{source: "Granoff", target: "Prince Lab", type: "3d-printing"},
{source: "Tockwotton", target: "List", type: "drafting"},
{source: "List", target: "Prince Lab", type: "welding"},
{source: "Prince Lab", target: "Prince Lab", type: "sand-blaster"},
{source: "Tockwotton", target: "List", type: "finishing"},
{source: "Tockwotton", target: "Prince Lab", type: "finishing"},
{source: "Tockwotton", target: "Tockwotton", type: "laser-cutter"}
];

var wood = [
{source: "Tockwotton", target: "List", type: "woodworking"},
{source: "Tockwotton", target: "Prince Lab", type: "woodworking"}
];

var metal = [
{source: "Prince Lab", target: "Prince Lab", type: "metalworking"}
];

var cnc = [
{source: "Tockwotton", target: "List", type: "cnc"}
];

var print = [
{source: "Granoff", target: "Prince Lab", type: "3d-printing"}
];

var draft = [
{source: "Tockwotton", target: "List", type: "drafting"}
];

var weld = [
{source: "List", target: "Prince Lab", type: "welding"}
];

var sand = [
{source: "Prince Lab", target: "Prince Lab", type: "sand-blaster"}
];

var finishing = [
{source: "Tockwotton", target: "List", type: "finishing"},
{source: "Tockwotton", target: "Prince Lab", type: "finishing"}
];

var laser = [
{source: "Tockwotton", target: "Tockwotton", type: "laser-cutter"}
];

function render(linkdata){  

    d3.selectAll("svg").remove();
    
    links = linkdata;
    
    nodes = {};
    
    // Compute the distinct nodes from the links.
    links.forEach(function(link) {
      link.source = nodes[link.source] || (nodes[link.source] = {name: link.source, type: link.type});
      link.target = nodes[link.target] || (nodes[link.target] = {name: link.target, type: link.type});
    });
    
    width = 960,
        height = 500;
    
    force = d3.layout.force()
        .nodes(d3.values(nodes))
        .links(links)
        .size([width, height])
        .linkDistance(60)
        .charge(-300)
        .on("tick", tick)
        .start();
    
    svg = d3.select("body").append("svg")
        .attr("width", width)
        .attr("height", height);
    
    link = svg.selectAll(".link")
    
        .data(force.links())
        .enter().append("line")
        .attr("class", "link");
    
    node = svg.selectAll(".node")
        .data(force.nodes())
      .enter().append("g")
        .attr("class", "node")
        .on("mouseover", mouseover)
        .on("mouseout", mouseout)
        .call(force.drag);
    
    node.append("circle")
        .attr("r", 8);
    
    node.append("text")
        .attr("x", 12)
        .attr("dy", ".35em")
        .text(function(d) { return d.name; });
    
    function tick() {
      link
          .attr("x1", function(d) { return d.source.x; })
          .attr("y1", function(d) { return d.source.y; })
          .attr("x2", function(d) { return d.target.x; })
          .attr("y2", function(d) { return d.target.y; });
    
      node
          .attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
    }
    
    function mouseover() {
      d3.select(this).select("circle").transition()
          .duration(750)
          .attr("r", 16);
    }
    
    function mouseout() {
      d3.select(this).select("circle").transition()
          .duration(750)
          .attr("r", 8);
    }
}

.link {
  fill: none;
  stroke: #666;
  stroke-width: 1.5px;
}

.node circle {
  fill: #ccc;
  stroke: #fff;
  stroke-width: 1.5px;
}

text {
  font: 10px sans-serif;
  pointer-events: none;
}