The formal name for this program is International Experience Canada. There is essentially nothing about it on the Canadian Border Services Agency site, other than explanations of how you can bring your possessions with you when you arrive. The Citizenship and Immigration Canada site wasn't much better but it turned out that was because the program has a site of its own.
Unfortunately, the FAQ for non-Canadians doesn't cover your answer. My guess would be that when it ends, it ends. If you want a month of not-working to do tourist things, you should do that during the term of the visa. The website doesn't seem too worried about whether you're working or exploring, since "The goal of International Experience Canada is to discover Canada" and they let you work so that you can afford to do that.
The contact page is useless, basically just says to talk to your embassy.