Edit in JSFiddle

$(".bar-colours-1").peity("bar", {
  colours: ["red", "green", "blue"]
})

$(".bar-colours-2").peity("bar", {
  colours: function(value) {
    return value > 0 ? "green" : "red"
  }
})

$(".bar-colours-3").peity("bar", {
  colours: function(_, i, all) {
    var g = parseInt((i / all.length) * 255)
    return "rgb(255, " + g + ", 0)"
  }
})

$(".pie-colours-1").peity("pie", {
  colours: ["cyan", "magenta", "yellow", "black"]
})

$(".pie-colours-2").peity("pie", {
  colours: function(_, i, all) {
    var g = parseInt((i / all.length) * 255)
    return "rgb(255, " + g + ", 0)"
  }
})

<span class="bar-colours-1">5,3,9,6,5,9,7,3,5,2</span>
<span class="bar-colours-2">5,3,2,-1,-3,-2,2,3,5,2</span>
<span class="bar-colours-3">0,-3,-6,-4,-5,-4,-7,-3,-5,-2</span>
<span class="pie-colours-1">4,7,6,5</span>
<span class="pie-colours-2">5,3,9,6,5</span>