There are many ways to do this, but the goal is to have the individuals with no coloring, and the parent cost centers with some color.
In a test case, I set a property named "Count" in my employee list to 1.
Then I added a line item to my report module to ask "If Employee.Count=1 then 0 Else 1"... then changed the line item Summary to "Formula'... so that Parents would equal 1 and employees would equal 0... in the way, regardless of the number of employee children, you can apply a consistent coloring format to the parents. You can lighten the tone of that coloring by setting the conditional formatting range to something > 1. See attached for example.
Kudos to @cgillett, I borrowed this technique from her.
Note: Employee.Count is either another line item in the module, or a property in the employee list. The idea is to have employees be 1 and all parents be zero (if in module, then set Summary to None, if in List, then parent list items will be zero in all cases). We do this so that our logic can ensure that all parents get consistent formatting.