iCloud: Change a calendar’s name or color
You can edit a calendar’s name and color at any time. (Though you can’t rename the Birthdays calendar.)
When you change a calendar’s color, all events associated with that calendar change to the new color.
Change a calendar’s name or color
Click Edit below the sidebar.
Do either of the following:
To change a calendar’s name, double-click the calendar’s name and type a new name.
To change a calendar’s color, click the Color button next to the calendar’s name, then choose a color.
The name and color changes you make are visible immediately in all the places you view this calendar (for example, in iCloud Calendar; in Calendar (or iCal in OS X v10.7.5) on your Mac; or in the Calendar app on your iPhone, iPad, or iPod touch).
Color changes you make to an iCloud calendar aren’t visible in Microsoft Outlook.