<div>
    <ul>
        <li><a href="@Url.Action("Index","Home")">Home</a></li>
        <li><a href="@Url.Action("Index","s")">s</a></li>
        <li><a href="@Url.Action("Index","t")">t</a></li>
        <li><a href="@Url.Action("Index","r")">r</a></li>
        <li><a href="@Url.Action("Index","y")">y</a>
        <li><a href="@Url.Action("Index","u")">u</a></li>
    </ul>
</div>

<li><a id="mylink" onclick="ChangeColor()"
     href="@Url.Action("Index","u")">u</a></li>

<script>
    function ChangeColor() {
        document.getElementById("mylink").style.color = "yellow";
    }
</script>