None of our 'stock' themes include the display function for UserGroup badges since by default we display forum ranks and special ranks which are more popular… Actually we need to discuss here whether we should add both in any case.
So - it means a small addition to the spTopicView.php template (in the /templates folder of the SP theme you are using).
the template function to add is sp_PostIndexUserMemberships() and you can find detailed informatipn on using it here: http://codex.simple-press.com/codex/api/template-functions-and-the-api/display-template-functions/topic-view/sp_postindexusermemberships/
I guess the most usual place to locate it would be beneath or instead of the forum rank badges so if you locate the display function sp_PostIndexUserSpecialRank() in the template you just need to either add this after, before or instead of.
As always we recommend that you create your own SP theme so that any customisation is not lost during a future update. (http://codex.simple-press.com/codex/themes/theme-basics/creating-a-theme/)
And I will re-open the discussion here in why we don't just put both in to supplied themes.
