Yes, it's basically a visual representation of the body modifications that were done to her, separating her from other humans. Story-wise, her blood flows very slowly, causing cyanosis in kind of an extreme way, and also allowing her a very steady hand, useful for a sniper.
Of course, the same story elements also mean she has almost no strong emotions so most/all of the Widow x whoever yuri doesn't work unless you ignore that part entirely.