The parameter tags_post_id has been around now for a while, helping you to display only tags that are assigned to a particular post or page (depending on the value, where 0 means the current item).
In response to a request, I have now created a new version (0.16) with another useful option: Rather than hiding unused tags, they receive a different class and can therefore be styled differently using assigned_class. 1
Two examples, each with the used shortcode on top:
[tag_groups_cloud tags_post_id=0 assigned_class=tag_assigned]