Edit in JSFiddle

Array.prototype.forEach.call(document.getElementsByName("radios"), function(input){
    input.addEventListener("click", function(){
        var radio = this;
        Array.prototype.forEach.call(document.getElementsByClassName("divs"), function(div){
            div.style.display = div.id == radio.value ? "block" : "none";
        });
    }, false);
});

Rojo: <input type = "radio" name = "radios" value = "rojo" />
Amarillo: <input type = "radio" name = "radios" value = "amarillo" />
Verde: <input type = "radio" name = "radios" value = "verde" />

<div id = "rojo" class = "divs"></div>
<div id = "amarillo" class = "divs"></div>
<div id = "verde" class = "divs"></div>

div{
    width: 15em;
    height: 8em;
    display: none;
}

#rojo{
    background: red;
}

#amarillo{
    background: yellow;
}

#verde{
    background: green;
}