Disregarding AVP Requiem, from what we've seen, the queen looks the same regardless of host. Unless of course the queen is birthed and develops adaptively to the type of prey in the vicinity. Perhaps, depending on the xeno locality, even the facehuggers are different to make it easier for implantation on the prey that is most common. It would take a fairly decent sized facehugger to implant an embryo into a jockey I would imagine.
So basically if the common host is human, the queen lays eggs that hatch facehuggers that are designed best for impregnating a human or at least something of similar size. But that might even go back as far as to say that every genetic line of xenomorphs differs due to the original host..... Which we know, so that would make it impossible for there to be a "pure" form, unless the xenos are in fact "manufactured."