Steps to reproduce:

1. Open Graph edit form with 2 items
2. Reorder, that 2nd item is 1st
3. Change color of new first item
4. Click save
5. Reopened form

Result:
Color is not updated. graph_color_not_updated.mp4
Expected:
Color is updated

Other scenario: If both colors are changed, then they are updated, but not to correct elements. graph_colors_reverse_order.mp4