Depending on which incarnation of the GS Cult you are looking at, you can arrive at a number of different conclusions as to what the structure could be.
The original works by Paul Murphy introduced The Genestealers which was basically just Patriarch, 'Stealers, & Hybrids. He then went on to introduce the Genestealer Cult which included the Daemon possessed Patriarch, the Magus, Limos, Hybrid Initiates, Rogue Psykers, Brood Brothers, Beastmen, Mutants, Mutant Bombs, Daemonic Familiars, Summoned Daemons, & Chaos Spawn.
Freebooterz gave us the Ork Genestealer Hybrid or "Bug Boyz" force in the RT Era as well.
Jervis and Andy Chambers then tweaked the GS Cult to be part of Tyranids and introduced Screamer Killers, Hunter Slayers, Squigs, Zoats, & Mind Slaves as part of the picture. Later on in the 2nd ed Tyranid Codex the GS Cult list was simplified, but added Hybrid Neophytes, Hybrid Acolytes, the Icon Bearer, & Imperial AFVs to the list.
The picture from "Tyranid" Tim Hucklebery adds in Hybrid Hierarchs, Cult Bodyguards, Brood Brother Initiates, Cult Truckers, Cult Attack Vehicles, The Genestealer Ark, special characters, Feral Cults & more classic PDF elements.
BoLs had their 4th ed incarnation adding some special characters of their own along with Seeding Lictors & Hybrid Monstrosity.
As you can see, there are more than a few units you could work into the list if needed. The one I would definitely try to include in your list is the Limo. It's iconic enough to be worthy of it's own place in the list.
