Create Graph with Data from 2 Cells

I have a spreadsheet that asks users a question, then scores the answers.
There are two groups of questions. At the end of each section (A & B I'll
call them) I get a total. In Group A, the possible range of outcomes is -17
to +17 which is in cell F20. In Group B, the possible range of outcomes is
-15 to +15 which is in cell F40. This column will be hidden.
On sheet2 ( I'd like to give the sheet a name) I have a graph in cells
C3:U19. In cells B3:B19 I have the B range list from 15 in cell B3 to -15 in
cell B19 by units of 2, except there is a 0 in the middle, so it goes 0, 1,
3, 5 up and 0, -1, -3, -5 down. Across the top is the A range list, C2:U2,
and is the same as B numbering except goes to 17.
What I want to do is COLOR the cell where the intersection of the results of
A & B from cells F20 and F40 on SHEET1 occur.
I have labels in Columns A, V and rows 1, 20 that I would like to keep there.
Thanks for any help!