The module is aimed more at simplifying the process of including a variety of social sharing services' default widgets. It provides the facility to configure the widgets in one place, but doesn't go beyond the configuration options provided by the widget providers themselves.
Styling the individual widgets is tricky, and if possible at all (many of them use iframes which makes things quite tough, for example), would need to be done on a case-by-case basis.
Likely not what you want to hear, sorry!
A positive side to all of this is that since we can't style the widgets easily, visitors are always going to be able to instantly recognise them for what they are.