The rest is up to genetics, you can stuff your fish to the gills with color enhancing agents, but if it's not in your fishes genetic make up then it won't help a lot.
FYI ..... the reason I posted that, is because many years ago I ran tests feeding fish that were red, massive amounts of natural astaxanthin (Haematococcus pluvialis) that was sourced from a company rep from Cyanotech, one of the largest producers at that time. I was attempting to make the fish more red, than when fed a diet of NLS. Keep in mind that next to hormones, this form of astaxanthin is about as potent in enhancing the color red as it comes. Too much for too long and yellow fish will turn orange. At the end of the experiment the fish fed massive amounts of this color enhancing agent were no more red than when the experiment started.
I posted my results, along with photos, on a well known cichlid site.
So how much more red, or orange in this case, a red devil will become is questionable, and will be based entirely on the color enhancing agents present in ones current food, with the rest being up to genetics.
I don't think that cichlid gold is lacking in color enhancing agents (part of the the OP's current diet), as there are probably millions of fish world-wide that are fed that as a staple, and even an exclusive, diet, yet any fish that I have seen have good color in the full spectrum. blue-red-yellow- etc. In fact, Hikari promotes their Cichlid Gold formula as a ....
color enhancing diet for cichlids, and go on to say,
Includes the highest grade of carotenoid available today, offering superior color enhancement while helping your pet retain their natural beauty year round. Can also help restore vivid coloration to washed out specimens.
Personally I would just stop feeding the Cichlid Staple.....
I will agree that the probiotics in this food (Parrot +) works, I have trialed that as well, with good results.