is there a way in vbulletin to make it similar to how Invision has, where u can make each certain usergroup a particular color and then have that displayed at the bottom of the home page?
In you usergroup settings you can use HTML Markup to get the colors. The legand at the bottom of the homepage is a simple statis template edit, but there are also a few hacks for it.
If you're using vB 3.0, and it might even work on 3.5, there's a template mod to list the colours at the bottom of WOL in the vB3.0 Template mod forums from recollection.