There are PDFs and ridiculously large TIFFs available for you to download and print [1]. Click on one of the images to see the respective download link. Just bring the PDF to a professional print shop and pick a size. At least that's what I'm going to do :)
These are oddly not available for "51 Pegasi b" and beyond though. Only PDFs for those.
I can get 40MB tiff files if I click on the "Download Printable Version" link at the bottom of the page. If you're still having trouble finding larger sizes, let me know which ones are problematic and I'll see about getting it fixed.