Caitlyn Jenner -- Ladies' Day Out (PHOTO)

Caitlyn Jenner celebrated her "truth" by hanging with her girls ... and paying her respects to transgender pioneers.

CJ posted a pic from behind herself and 5 anonymous GFs looking out at the Malibu hills ... from what appears to be her backyard. Guess they weren't into the Belmont Stakes.

She included the caption, "Learn from those who have walked the path before you. #TransIsBeautiful."

As we've reported ... Caitlyn's docu-series will focus on her relationships with girlfriends.