Google Docs makes it easy to collaborate ... but it doesn't track the changes with any color coding. The editor must manually color-code to track changes while editing, whereas Suggesting mode ...

The entries that you input into your Google calendar can be edited to correspond to a color coding system of your own choosing. By default, your calendar entries will all display as the same color ...

Google Docs is a free word processing software ... "Custom" from the drop-down under "Page Color." You can input an HTML color code, for example, or play around with the tool to find a color ...