This way
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function () {
$("select").change(function () {
$(this).find('option').css('color', '#222');
$(this).find('option:selected').css('color', '#a1c3d2');
});
});
</script>
</head>
<body>
<form id="form1">
<select>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
</form>
</body>
</html>
Demo