My concinnus all are very different, you can have a look at pics I posted earlier :
Some pictures of my snakes :)
There is no difference whatsoever in the food and they have not been offered any supplements to intensify the colour, but they are all of different bloodlines. So I think a lot is already in their genes. I don't say supplements will help, but it's not needed to have a deep colour in my opinion.
The intensifiing of the red and fading away again when they are getting old is something that's indeed observed often.