Is it a catholic christening??
If it is then yes she can - for the first bit, in fact i think it would be fairly good. In a catholic ceremony they are supposed to wear a dark colour and then when they are baptised they change into the white, to represent the removal of original sin. Can't speak for a non catholic ceremony.
I would however question why you are bothering to have her christened if you want her to wear red all the way through, christening is symbollic after all so........Im sorry, if i were in the congregation, i would be getting my Ms Judgy pants ready.