I don't know why some people seem to think that orange is McLaren's traditional colour. Possibly because that (well actually Papaya, which is more of an egg-yolk yellow) was the colour that the cars were when the music stopped for Bruce McLaren. In reality, F1 McLarens were only orange-y for four seasons: 1968, 1969, 1970 and 1971 (though it continued in Can-Am for longer). For 1972 it was mostly replaced by Yardley white, black and brown and when Marlboro took over as main sponsor the orange went completely.
Before 1968 F1 McLarens were turned out in various colours. The first McLaren F1 car to race, the M2b in 1966 was white with a dark blueish green stripe. That was followed in 1967 by the F2-based M4B, which was red with a white nose. The 4B was then superseded by the M5A, which was red with a dark blue stripe.
If you go back to the first racing car McLaren produced, the Group 7 M1a, that was black with a broad silver stripe, reflecting the New Zealand sporting colours used in rugby, soccer etc:
When national motor racing colours were first created, former British colonies were generally allocated British green plus another distinguishing colour - hence the green and gold of Brabham. New Zealand's distinguishing colour was silver. The silver fern is also the national emblem worn by New Zealanders representing their country in sport. So there is a good argument that if McLaren has a traditional colour it would be silver/chrome.