Unable to assign 6 colors

I have 2 columns, name and things. The column name has names of people and the column things 6 activities like A,B,C,D,E,F and has been set data validation function. I just assigned 3 colors for A,B,C by using Conditional Formatting, but it allows only 3 conditions.

My question is that there is any method I can assign 3 more colors for D,E,F? Please help.

Please find attached file for your reference.