Are all the stars significant? If the bulk of the starscape is background, you want some way to have the ones you're concerned with stand out - bigger, brighter, flares, symbols - something.
If the stellar class doesn't matter to the user of the map, might as well make them all the same color. But if, say, your students at the stellar nav academy need to remember NOT to route passenger liners past the blue-white gamma-flooding flare star, then by all means, show color.
Starfields are easy to *depict* but hard to *map*. A useful display on the bridge of a ship for instance might focus on just the stars that have jump gates, or that have inhabited planets, or some other important characteristic. And since most look alike to the naked eye (okay - similar), meaningful symbols might be better than bright dots in a black field.
As to scale of the map - if you treat a broad enough swath, the flat-spiral structure of a typical galaxy somewhat constrains your z-direction. If you're in the middle of a globular cluster with just as much z-axis in play as the x and y though, then it's going to be tough for a reader to discern that the two adjacent stars marked z+255 and z-397 are way, way further apart than the two separated by 80 LY in x-y, but at about the same z.