No offense, but do you really have 3 red tail cats and 2 silver arros in a 55?
Stocked in that manner, you could easily fit 40-50 adult male peacocks in a 55.
Seriously though, you could keep 5-6 adult male peacocks in a 55, but they'd need to be different colors, otherwise they'd beat on each other and only 1-2 would color up. This sort of defeats your purpose.
You could try a group of ruby red peacocks with 2-3 males and 6-8 females and 2 1/2 of the males may color up. I wouldn't try it with with any jacobfreibergi - they're pretty rough and most likely only one will color as adults.
Alternatively, you could set up a 75 with red empress - they are blue and red. In a tank that size, you could only do 1M/3F though.