Navigate to the scene you want to edit the object in or add a new object.

Click the object to select it.

 The "Modify" menu in the right-hand sidebar opens automatically. 

Select the color pallet icon in the menu. 

Change the color of the selected object by clicking on one of the colors.

Proceed working on your project - changing the color does not require extra saving, the new color is saved automatically for your onbject.