Oh my! She appears alert to me. I also would wait and see. Definitely keep her warm and away from the other birds. She also does not appear in shock IMO. That is quite a wound and keeping it clean will be very important.
4 days ago my chicken , Sweetheart , was attacked by a Fisher. He actually ATE through my chicken wire and dragged her out of the hole he made in the wire. She appeared dead with a neck injury. She also had a blank look on her face and did not eat until TODAY!!! I brought her in my home and put her in a wire crate. Tried feeding her by hand and she just looked off into space and moved her little beak. Today she started pecking at the ground so i fed her canned fruit and a little cheese. She is not out of the woods yet but certainly has a fighting chance. Her wounds were not as extensive as your chicken. If you have a vet who could stitch her maybe that would be
a suggestion. However, don't give up....if she takes a turn for the worst you will notice it for sure and

could then choose to put her down. We certainly learn about resiliency and courage from our chickens. Maybe keep your other chickens locked up for a bit to discourage the predator.
Best of luck to you.....I will be rooting for your courageous girl. Regards,