Original I140 is company's property, it make sense that company keep it. Photocopy of I140 should be good enough for you to do anything.
However, perhaps you need get the job deion on your LC (if you are RIR/Perm based), for your new employer lawyer to evaluate your I485 portability.
However, perhaps you need get the job deion on your LC (if you are RIR/Perm based), for your new employer lawyer to evaluate your I485 portability.