Green’s Dictionary of Slang

pinky n.2

also pinkie
[the image of SE pink as a ‘feminine’ colour]

a passive or ‘feminine’ lesbian.

[US]Trimble 5000 Adult Sex Words and Phrases.
[US]B. Rodgers Queens’ Vernacular.
[US]Maledicta VI:1+2 (Summer/Winter) 132: Pinky (femme or passive lesbian).