My brain is always packed full of stuff after a session. I like to write in my journal immediately after session. This serves both as a way for me to process and decompress after talking, but also it serves as a record of what we did and talked about so I can remember it for next time.
If you aren't able to do this as soon as you get home, could you maybe keep a notebook in your car and journal in the parking lot before you drive home? Or maybe you could make notes in your phone before you get home.
If you don't like to write, as others have suggested you could take an aimless drive. You can even talk things out, out loud, to yourself it's not weird. Everyone does it! (I think)