Note, I certainly see what you're talking about, not trying to apologize for the image.
As was mentioned earlier, travellermap.com is the "go to" "atlas" of the Imperium, but that doesn't excuse the show map.
If you click on this, this is essentially the same map:
https://travellermap.com/api/tile?x=...7&style=poster
But unfortunately, the areas aren't labeled below the sector name (like the League of Antares).
You need a higher resolution map, but you run in to limits with travellermap in generating one at that resolution.