iCloud: Change a calendar’s name or color
You can edit a calendar’s name and color at any time. When you change a calendar’s color, all events associated with that calendar change to the new color.
Note: Calendar name and color changes you make appear on every device that has the iCloud Calendar feature turned on. You can’t change the name or color of the Birthdays calendar.
Click Edit below the sidebar.
Do either of the following:
Change a calendar’s name: Double-click the calendar’s name and type a new name.
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 iCloud Calendar and in the Calendar app on your iPhone, iPad, iPod touch, or Mac. Color changes you make to an iCloud calendar aren’t visible in Microsoft Outlook.