You cactus is changing color because it is stressed. Depending on how often you water it could be water stress or if you have recently exposed it to more sunlight it could be sun stress.
In both cases giving the plant a little more water than normal could help change it back to more green colors, but it is not uncommon for these kind of cacti to remain in their stressed look for months at a time.
Some cacti will flower every year without any help, others will not and with those there is not that much you can do. For some a little bit of bloom stimulating fertilizer in the spring can help, but in my experience it is hard to determine beyond doubt that that has a direct effect. I think it has some effect.