There was no standard color. Some 5" HVAR's were natural metal with OD warheads. Some had the tip of the warhead painted yellow and some had a yellow stripe behind the warhead. The rockets were sometimes painted OD with silver warheads with a yellow tip. Some warheads were painted yellow with a red tip ( WP's). I have even seen pictures with red warheads and natural metal tubes. I think these were special rockets used for heavy armor or trains.
Berny
Phormer Phantom Phixer 
On the bench
TF-102A Delta Dagger, 32nd FIS, 54-1370, 1/48 scale. Monogram Pro Modeler with C&H conversion.
Revell F-4E Phantom II 33rd TFW, 58th TFS, 69-260, 1/32 scale.
Tamiya F-4D Phantom II, 13th TFS, 66-8711, 1/32 scale. F-4 Phantom Group Build.