There isn't a way to view a group to see a list of campaigns previously sent to that group. The reason is that group membership is fluid -- So you might see that Campaign ABC was sent to Group 123, and Sally is a member of Group 123 but wasn't a member at the time Campaign ABC was sent to the group, so she didn't receive it. We've found that folks are more interested in learning which individuals received a certain campaign than they are in which group received it.
That being said, you can find out which groups you sent a campaign to by going to the Response page and clicking on a sent campaign. There's a To field in the lefthand column that lists the individual email addresses and groups. If you sent to many groups, you'll see a clickable ellipsis that expands the list to show all of the addresses/groups.