A calendar is identified by its name and color, which you can change at any time.
Changing a calendar’s color changes the color of all of its events. If you want an event to have a different color, either change the color of the whole calendar or move the event to a calendar with a different color.
If you don’t see a list of calendars on the left, choose View > Show Calendar List.
Double-click the calendar’s name in the list, or force click the name. Type a new name for the calendar.
You can’t rename the Exchange calendar named Calendar.
If you don’t see a list of calendars on the left, choose View > Show Calendar List.
Control-click a calendar’s name in the list, then choose a colored circle.