Have you considered Clip Art library content for your Outlook signatures? A quick step to this feature would be the Email signature template from the Office Online Templates library. This template contains professional layouts you can copy and customize within Outlook, with two of these layouts designed for both image and text. (For additional instructional assistance see also the Office Online Products section of Signatures tutorials -- including Change your e-mail signature and Create and include a signature in outgoing messages).
And finally, a different option for the Outlook signature is closing with an Electronic E-mail Business Card that really integrates text and background.
See this article on Office Online Products for assistance: Add or edit an image for an Electronic Business Card. And, among the keyword searches previously mentioned, consider a general background image to stylize this card.