My daughter 7 1/2 months old has a really bad diaper rash, I noticed that the skin covering her vagina the " lips" have a blue color is this normal?

No. See pediatrician for evaluation. The bad diaper rash may be bacterial or candida infection? Blue color is closer to purple this could be blood underneath skin which signifies damage deeper in skin.
DIAPER DERMATITIS. M ost of the diaper dermatitis are caused by fungus infection. The blue discoloration may be due to the severity of infection. Always wash with soap and water when changing diapers. Your md will give antifungal cream for it.