Totally get this struggle with my father in law. Started using colored tape to mark where every tool goes on the pegboard. Blue tape for his stuff, red for mine. Now he puts things back in the right colored zone without even asking.
Actually that colored tape system only works if you never share tools. What happens when you both need the same socket wrench, does it get two homes? Labels with words seem clearer for shared items. My uncle tried the color thing in our family garage and it just led to more arguments. You end up debating if the tape is more blue or more green instead of just putting the hammer back.
Honestly debating if tape is blue or green sounds like a bigger problem than the tools. Just write the name on the spot like @blairm93 said and be done with it. This isn't a library system, it's a van.