1. Go to Configration - Host - Graphs - Create new Graph
2. Add Items
3. Click on Color picker - overlay is shown.
4. Click again on the same spot
4.1 Or click on any empty space on the page.
Color picker is not closed.
Color picker is closing on clicking again on color icon, or empty space, or [x] button in the upper right corner of overlay, as it is happening with any other overlay (for ex. calendar).