I'm still working my way through season 5 of Mad Men and noticed the art in Peggy's apartment. I was reminded of my Robert Lyons art and thought it might actually be by Lyons for a second. The thick outlines are similar to the Lyons art I've seen, but they're also pretty reminiscent of the time. Looking a little closer it almost looks like layered cloth or some other texture, not paint or a print.
After countless searching I'm positive it's not by Lyons, but have no idea who the artist might be. If you happen to know who the mid-century artist is, please let me know in the comments.