Colouring a polygon on a map

Hi,

I have a series of polygons on a map. Is there a way that I can colour them in different colours depending on a value fed in (for example, from an XML file I gave

<polygon1>
 /* list of points */
 <color>Green</color>
</polygon1>

which results in a green polygon, I could equally have yellow, orange, purple etc)

Thank

Paul