It has been quite a while since any new features for the Night Elves were datamined, so I played with Photoshop to see what additional colors we could get for their facial markings (obviously on both males of females, although I only edited the females as it was much easier).
The new colors are: pink, blue, light blue, golden, auburn, white, black.
Most of the shapes are either from the current game files or based on them, with the exceptions of the last two (white and black) which were inspired by the minimalist markings Azshara displays in the Warbringers video and the theme of the Night Warrior.
I am obviously assuming that all shapes should be available in every color and separated from skin/hair color, but I don’t think you really need me to create a different preview file for every skin color to show all of the possible variations.
Enjoy! 
https://i.ibb.co/2ht6yXP/new-nightelf-markings.jpg