You could take the map image and save it into a handout that you provide to players, so they could reference it anytime they want in the sidebar. You could copy the page and remove all the NPCs and dynamic lighting lines, and move the players to that first, then move them to the map with NPCs when they encounter them. But Kraynic's suggestion is what most GMs will do. If you have advanced keyboard shortcuts turned on, then it's a simple matter of a few keystrokes to switch to the GM layer, select the relevant NPC tokens, and move them back to the Object layer. (k, mouse select, l o) But if you're looking for a way to give a token vision of only the Map layer but not the Object layer, then no, that is not possible.