Welcome, so glad you joined us. This is a great place to be. If you Goggle adult bib patterns, you should get a few hits, but here are a few that I found:
http://www.sewing.org/html/bibs.html
http://www.angelfire.com/planet/mcsh...epatterns.html
http://www.laurassewingstudio.com/NL/060407/060407.html