Office 365 (Outlook 2016 for Windows) - Organize your calendar with color categories
To see more categories or to create a category, click All Categories to open the Color Categories dialog box. To assign a color category from the Color Categories dialog box, you must select the check box next to the color category. The Color Categories dialog box is also a quick way to assign multiple categories to an item.
The first time that you assign a default color category to an item, you'll be prompted to rename the category. At this time, you can also change the color of the category and choose a keyboard shortcut.
- On the Navigation Bar (Navigation Bar: Commands at the bottom of the Outlook window that enable you to quickly navigate to Mail, Calendar, People, and Tasks.), click Calendar.
- Click a calendar appointment, meeting, or event.
- Click on Categorize.
When you assign a color category, that color is used as the item's background color on the calendar grid.
Tip You can change the name of any category. Click an appointment, meeting, email message, or contact, and then click Categorize > All Categories. Click a category, and then click Rename.