Maybe I am misunderstanding your question, but out of the box there is an assignment group column on the Approvers related list that shows the group that the user is approving for. Is this what you are after?   If there are multiple groups required to approve the record at the same time then you will see multiple groups show up in the list for the various members.

Thanks Michael. So I added this column but strangely, this is what shows up as the listed groups. They're definitely not what these groups are called though they point to the correct groups.

Thanks for the tip. That worked out.

Isn't the approval history helpful?

http://wiki.servicenow.com/index.php?title=Task_Table#Important_Task_Table_Fields