Here the detailed PDF maps
The zip.file has a size of around 700k , but there are 4 maps of the IS from 4 different eras(2705 - 3058).
The maps provide an overview of the IS and they can be zoomed in deeply - every single planet is displayed.
If you don't have the Acrobat Reader shareware which is recommended to view the pdf.maps , use this link to get to a page from where to download it.