Kind of i try to keep the same image through out such as the icon/logo so its easy for people to reconise that the pages are linked to the main site. brand awareness somtimes is key so that others do not mistake who you are and what you and your site, content is about.
When it comes to having social media graphics on my site I do try to get them to match the color scheme of my site so that it looks better. I am someone that hates to see something out of place so I try to get the graphics as close to the color scheme as possible if not exactly.