I am afraid Swing overall is not the best tool to print something, even if it generally allows you to.
Default L&F might look a bit better in printed form due to different fonts used and less graphical details. Basically when printing occurs the whole UI element you are printing is scaled to the page size and that might look just ugly in some cases. Swing UI is generally pixel-based and uses images to create the final UI view and render it onto the screen, so when you are printing it some optimizations may be done due to the flag set but it will still look pretty bad.
A good way to print tables like that is to create some PDF or DOC based on that table and print it instead of the UI element. Though this solution have other issues and might not be the best one for all cases.
So I'm not really sure how I can help you with this case.