A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
The Color Picker is provided by macOS so the first corrective measure is to restart the Mac. That often cures a variety of ills, especially if it hasn't been done in a while.
If the problem persists confirm that your version of both macOS & Office are fully updated. If you provide the current Version Numbers of both they can be verified for you.
Should the issue persist after all is known to be current, start the Mac in Safe Mode to see whether the problem may be due to an add-in or background operation.
Explain all results here.