Here is my idea about the proceedings. I tested it using superstore data.
I filtered data just to get 2 segments as in your case.
Now I calculated distinct count of segments (i.e brands in your case).
Using this count I created a calculated field as below.
Here: Calculation 2 is distinct count of Segments.
Using this field I could get below colors.
Definitely for multiple brands you may have to select another color, as I don't see a way to get gradient over there.
Is any Formatting in terms of color gradient possible?
I doubt if gradient would be available with discrete options