ItemCreated

<div id="treeMap"></div>
<script>
    $("#treeMap").kendoTreeMap({
        dataSource: {
            data: [{
                name: "foo",
                value: 1,
                color: "red"
            }]
        },
        valueField: "value",
        textField: "name",
        colorField: "color",
        itemCreated: function(e) {
            e.element.css("background-color", "blue");
        }
    });
</script>