That's because it isn't open yet. Before each of the groups were open, the same thing happened on them. The team chose a picture of one of the players from each list to represent it - McManus for QB, Bethea for RB, Scott for receiver, etc.. That's the same picture that appears for each list when you first go into the site.
Once voting is open for coaches, the full list will appear. And I'm sure it will include Trimble, Sazio, Bruno, and (obviously) Lancaster at the least. My guess is it will also include Voyles and Williams, as they are the other coaches who have won the Grey Cup as Ticat coaches, and possibly Shaw and Marshall, both Coach of the Year winners. But Gaudaur never coached the Ticats, as far as I know, so he won't be on the list.