<style>
.default{color:black}
.apple{color:red}
.banana{color:yellow}
.orange{color:orange}
</style>
<select class="default" onchange="this.className=this.value">
<option class="default" value="default">Select with few options</option>
<option class="apple" value="apple">Apple</option>
<option class="banana" value="banana">Banana</option>
<option class="orange" value="orange">Orange</option>
</select>