If your daughter’s confirmation instructor did not say anything, wear any color your daughter or you like. What you should avoid are spaghetti straps and strapless stuff. A nice “church” dress from Easter, if she has one, ought to do the trick. There is no prohibition, per say, against black, unless the parish or diocese has one. Red and white are traditional confirmation colors.
This is why they used to have red robes for the boys, and red and white robes for the girls.