Either one is correct. About the time the Panther came into production, the German Wehrmacht (Army) decided to change from German grey to dunkelgelb (dark yellow). This is a very mustard looking yellow. Most new vehicles were issued in this base color for the remainder of the war.
Additionally, at this time, a red brown and a green paste were issued to with the vehicles. These pastes were a do-it-yourself camouflage kit. The pastes were supposed to be thinned with paint thinner and applied by the crews as they saw fit. Some crews used thinner, others used fuel, some used water and others just smeared the paste on. As you can see, the schemes would look quite different from vehicle to vehicle based on crew skill and other factors. Even the type of thinner used would effect color. So have some fun with it.
As far as the kit itself, Airfix 1/76 scale kits (sometime along the way they changed the listed scale from 00 to 1/76 to 1/72 but is the same kit!), they are older kits that have seen better days and most have been bypassed by superior modern kits. Especially true of a mainstream subject like the Panther.
Some people swear by them and most will build up into nice little kits. Just use caution when mounting the tracks onto the suspension. For a kit this scale, the mounting pins for road wheels and sprockets are not that big and the pressure used when stretching the tracks over the wheels may snap off one of the idlers or sprockets.