When you initially set up your OpenSimSim company account, all Positions added through the setup wizard have a default color of Blue. These can be subsequently updated and assigned a color of your choice from a palette of twelve colors. By doing so, this will facilitate easier recognition of shifts when working with the Schedule.
Navigate to Main Menu > Positions. All positions associated with your company will be displayed.
Click on a Position which will present the attributes of the selected Position, including the ability to assign a color of your choice.
Select the desired color and click on the 'Save' button when done.