Used it myself for Cairns.
Update:
Youth Hostelling Association of Australia. Low cost accomodation, mostly dorms/shared.
I used it myself as a single traveller but shared a dorm with 3 others. One bathroom in the dorm. Food/catering is extra, not included.
I suggest it as you are a large group so this could suit you if you divide your group into several dorms.
Staff were fine – you can book tours from the main desk.
Try this site:
Yes I am affiliated with hostelzoo, but I took a group to the Cairns Central YHA and had a really great time.
Have fun no matter where you go.
I haven’t used the site specifically for Cairns, but I have found some great places using the Stayz http://www.stayz.com.au/ website.
You can usually find a variety of places (large house, guest accommodation or cabins etc.) to cater for a larger group.
The prices are generally better than a typical hotel or hostel, the people are generally nicer and the range of activities are usually better (many places provide equipment such as kayaks or big screen TV or fishing equipment etc.).
I am not affiliated with this site, just a very pleased customer.
Credit:stackoverflow.com‘