Calendar Groups allow you to quickly see the calendars of people you frequently work with. Add members to a Calendar Group, then use the Calendar Group every time that you want view those same calendars. Important note: YOU MUST HAVE PERMISSIONS ASSIGNED TO ACCESS ALL CALENDARS BEFORE HAND. To create a Calendar Group for to Calendar > Home > Manage Calendars > Calendar Groups.
Figure 1: Calendar Groups drop down
Now define the users-calendars you wish to add to this group:
Figure 2: Address Book, select Calendars
Click OK once you have specified all names you wish to group.You will now see the new calendar group you have created with all Calendars listed that you specified in the step above.
Figure 3: Calendar navigation pane