Use custom colors for events on Google Calendar
By default, Google Calendar only provides a few predefined colors for Events, which is often not enough. Using Event Colors, you can easily pick custom colors for events.
Event Colors will add a new color box next to the others so it fits in. Clicking it will bring up a color picker where you can pick a new color. After picking a color, it will add the new color after the color picker, where you can select to use it.