Here, I wrote a quick product for you (attached) to make your life far easier. This will also allow it to easily move across forum upgrades without relying on template edits. Install it as you would any normal plugin. Once you have it installed go to your Admin CP then click on Plugins & Products then Plugin Manager.
If the "Title Group" plugin is not active, make it active. Open it for editing...
Code:
// Admin Usergroup
case 6:
$tg_imageURL = "http://urltoimage.com/image.gif";
$tg_linkURL = "http://linktopage.com/page.php";
break;
Copy and paste that for every usergroup you want to have a custom image. Replace the "6" with the ID of the usergroup and the image/link URLs with your information.
If you have any questions post here... I wrote this quick and tested it and it worked, but I may have missed something. ;p