thats easy, but as I don't know gerrit I need some information...
the gerrit plugin seems to have quite some different types of causes (Gerrit Cause, GerritUserCause, GerritManualCause,...). can you please attach some build.xml's of the different builds you would like to have cause expressed with an icon.
these builds should be from jobs having the "Build Trigger Badge Plugin" active.
Actually, I'm only interessted in this section of the build.xml's:
<cause class="hudson.model.Cause$UserIdCause" reference="../../hudson.model.CauseAction/causes/hudson.model.Cause_-UserIdCause"/>