"What color is the new refrigerator?"
Translation:Jakiego koloru jest nowa lodówka?
The main answer is "Jakiego koloru jest ta lodówka?". "jakiego koloru" is Genitive here, it works like "Of what color is this refrigerator?" and as usually, 'of' suggests Genitive. Then you can answer "Ta lodówka jest koloru pomarańczowego", using Genitive as well, but a more probable thing is to simply say "Ta lodówka jest pomarańczowa".
An Accusative option is to say that the object 'has' some color. "Jaki kolor ma ta lodówka?" = What color does this refrigerator have? - 'jaki kolor' is in Accusative here, because of the verb "mieć".
The meanings are basically the same.