No not color, but rather grouping.
For example:
Metallic dragons are 'always' good (as in 99 out of a 100 metallic dragons are good)
Chromatic dragons are 'always' evil (these are the nlack, blue, green, red, and white (and purple, yellow and orange) dragons)
Gem dragons are 'always' neutral (interesting to not that the obsidian dragon is NE)
Color isn't really an issue, as emerald dragons (a gem dragon) are green, song dragons are silver, but are not always good, and so on. Color is not an indicator, species is.
And besides, you should not draw paralels between mythic creatures such as dragons and humans.
Later,