Back in 2009 i found this application called Campaign Cartographer 3 by pro-fantasy software. The CC3 software has built in functionally to create sector maps, however the graphics use for the planets are a little blah… So I looked into creating new planet graphics for the application.
Within the application you have the ability to create symbol sets for use in your map.
Here is the download if you would like to add new Traveller Planets to your sector maps in CC3. (Including instructions on how to add the symbol set in CC3)