Perhaps, although it does differ from branches for instance, the navy and RAF usually wear blue berets whereas the Soldiers on the ground would have green maroon khaki etc ( Excluding the RAF regiment, i dont know what they have as beret colour etc)
Also i dont know how practical berets are in airsoft, they might slide about and fall off, but if you have it tight it hurts a bit, i personally wouldn't wear one but if your team wants to,go ahead