To color-code your folders
Although the default folder color is Manila yellow, you can change the color of any existing folder to one that helps you organize your items. Color-coding is useful when you want to find items quickly by importance, based on your own personal color preferences.
In the Folders pane, select the folder or subfolder whose color you want to change.
Click the right mouse button, and then, on the shortcut menu, click Folder Color and select the color,
— or —
click Properties and in the Color box, specify the color you want to use.