seating based on schedule and department

Hi, I need to do a seating plan based on schedule and department. I don;t even know where to start. My floor plan is ready.

floor plan is based by colors.

I need to be able to put how many tech work from 7:45
same thing for tech starting @ 8 and then how many start after 8
I need the employee from the same department and similar shift to work together!

I know it's a big project and that's why I ask your help!!