No. Although Google does do some basic checks in the stylesheets (apparently, cloaking text by making it white on white will be detected) Google does not pay attention to the graphical aspects of a site.
If they did, the entire market for free themes would collapse, just think about all those major vBulletin forums that use the default skin... And what about all those Wordpress blogs that come with the default theme.
If a unique design would be a prerequisite for a good SEO score they would soon cost hundreds of dollars each. Google is about finding the most relevant content, not about finding the most unique designs.