how do I set static routes in windows domain to all computers at once
Yes you can do it via GPO. Locate a GPO location that works for you (such as per site) that hits all the computers you want to hit and link a GPO there. Put a batch file in Computer Configuration -> Windows Settings -> Scripts (Startup/Shutdown). Configure that batch file to run the route add commands that you want the computers that are within the scope of that GPO to execute.
Also your lab sounds weird. A test lab of 500 hosts each with 4 physical NICs? Wow.