Straight strategy:
First part you need to stay low so that the Golem only RUNS at you and not JUMPS at you, Beast form might be helpfull for evading him once he is running.
You need to eat the small buggers that comes out of the Golems head when the lady scratches or pokes or pets it or something, then you have to shoot the lady, with the thing you just ate, when you hit her the Golem gets vulnerable and you can attack him.
Once the lady starts shooting too (about 2 or 3 times of shooting the Golem while vulnerable), the Golem gets totally vulnerable, so you can just keep shooting at him.