Do the colors of the couches in No Exit symbolize anything?
While the particularity of the colors themselves don't seem to have any obvious symbolic meaning, the fact that the colors are different shows a symbolic difference between the characters. Each couch has a separate angle and color, which symbolically shows the significant difference in the characters, as well as in how they see each other.
Furthermore, the colors and angles of the couches serve as a method of giving personality to the three characters in the play. Estelle, for example, chooses the blue couch in order to match her dress. Both Inez and Garcin offer their couches to Estelle, for they aren't too caring about the colors of their couches. Estelle, of course, becomes possessive of her own space and even scolds Garcin for later sitting on her couch.
For another example, Garcin's paranoia is shown through the colors of the couches; he is irrationally convinced that "they" had planned all the particulars in regards to the couches, such as their colors and positions and angles. In a sense, his attempt to decipher why each couch is the way it is can symbolize readers' tendencies to search for meaning in nothing.
Like the people in the room, Garcin, Inez, and Estelle, the couches of "wine-red," "livid green," and blue clash with one another. They are also in the Second Empire style which is tediously overdone so as to irritate anyone who likes clean lines. Estelle complains that she "loathes angles" and Inez complains of the Second Empire style of furniture, remarking that "The room was all set for us." She also tells the others, "And they've put us together deliberately."
The few objects in the room have symbolic meaning, especially in defining the characters. The sofas are of different colors—wine-colored, blue, and green—and Estelle insists on taking the blue one because it best matches her dress. This symbolizes her superficiality.