There is the Disney Shuttle bus, however with your larger group others have recently posted about private van transfers. You can search the forum, several chats within the past two weeks.
We took super shuttle for our group of 8. It was cheaper to do the private van service, they came right away to pick us up after we got our luggage and it was only us in the van. Several companies offer it, but Super Shuttle is who our travel agent works with. We had to provide our own car seats if you have kids who need them.