No. Ideally, players aren't supposed to be any more special than NPCs. The only plausible way to make that work, then, would be for Universal Cartographics to show you the density of members of any arbitrary system faction (players of course would be members of the Pilots Federation, which is a system faction in-game that only has any influence in Shinrarta Dezhra). To show population density by system faction would be impossible because NPCs are not persistent, there are far too many factions to filter by, and it would be strategically unsound for any faction to allow a cartography company to track the locations of their ships.
If you want to know where most of the players are, all you have to do is use a little intuition. Most players never go very far from the starting systems - so LHS 3447, Eravate, and the few surrounding systems. Most of the rest will be present in popular trading hubs, particularly the "rares loop" around Lave and Leesti. You'll usually be able to find one or two players at most other stations that sell a rare commodity, as well.
