cesarr,
вариант с делегированием перекрасит и восcтановит прежний цвет у любого div )))
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<style type="text/css">
#w,#z{background:#FF0;border:#000000 1px dashed;display:inline-block}
div>div{background:#00F;color:#000;width:60px;margin:8px;float:left;border:#000000 1px dashed}
div>div:last-child{background:#F00}
div>div:first-child{background:#FFD700}
</style>
</head>
<body>
<div id="w">
<div>1</div>
<div>2</div>
<div>3</div>
</div>
<div id="z">
<div>4</div>
<div style="background-color: #00FF00">5</div>
<div>6</div>
</div>
<script>
document.querySelector("body").onclick = function (a) {
var b = a && a.target || window.event.srcElement;
if ("DIV" == b.tagName) {
a.stopPropagation ? a.stopPropagation() : a.cancelBubble = !0;
a = window.getComputedStyle ? getComputedStyle(b, "") : b.currentStyle;
a = a.backgroundColor;
var c, d = b.getAttribute("color");
b.style.backgroundColor = d ? (c = "", d) : (c = a, "white");
b.setAttribute("color", c)
}
};
</script>
</body>
</html>