Through the tab for Calendar -> Administration -> Calendars
It would be tremendously helpful if in seeing that list of users with Calendar, there was also one more column after Name & Owner
Adding the column for Permissions and showing which "Authorized Groups" the user has attached to them would be a huge time saver.
It would enable the Admin to instantly and easily see which group(s) that user's calendar is part of, instead of having to double-click on each and every individual account to review the status of it. When you have a large number of users, and you need to do maintenance and review, or if there have been organization changes that call for some re-organizing of people, it requires a great deal of time to have to check each calendar group permission one by one with the current condition.