When I was stalking lolipower for White Album downloads, I came across this picture. At first it would appear a typical anime art, but we should take care to notice the gender roles.
Boobs. We can see them on the person on the left. There are a few more visual clues: blushing, the red head thingy, the partially opened mouth. But most importantly, her position vis-à-vis the other person, she is “on bottom”, or, rather, the person in blue is holding her.
But because the two characters are virtually undistinguishable based on non-contextual appearance alone (the “guy” is very androgynous), this just shows how socially constructed signs and clues can engender gender (sorry, had to say it) moreso than, well, the site of gender itself, anatomy and people.
Here is my photoshopped version:
What I did: removed the hand on the red blouse, switched oral expressions, [terribly] added blushing to person on right, removed ahoge.
Does it look more yuri? I dunno, probably not. But you get the idea.