The original title of Ntozake Shange's play is "for colored girls who have considered suicide/ when the rainbow is enuf" (complete with the unorthodox capitalization, spelling, and punctuation).
In the original play, the characters did not have names, and were known instead by the colors of their costumes: "Lady in Red", "Lady in Purple", "Lady in Blue", "Lady in Yellow", etc. Although the movie's characters do have names, both the movie and its advertising continue the color-theming of the characters.
The trailer for the film is scored with a cover of Nina Simone's 1966 song "Four Women", which (like the play this movie is based on) tells the stories of several African American women who have had to deal with societal ills caused by the legacies of slavery and racism.