Colour Cells Based Upon Value of Another Using Formula

Hello

I wanted to colour specific cells based upon the value of other cells.
The attached spreadsheet is a gantt chart.

I would like to achieve:

Shade cells in row 7 on wards, based upon the corresponding selection of F7, G7, H7, I7
As you will see I have labelled rows 3 & 5 with the same values as appear in the drop down lists of columns F-I.
I have shaded what I want to happen in the relevant cells in pink.

I want this to happen automatically using a formula if possible?

Any help much appreciated
Thanks Debbie :O)