1. Holders of a (blue) Canadian Travel Document for refugees issued on the basis of the Geneva Convention of July 28, 1951 (note that this is not a regular blue Canadian passport for Canadian citizens) and
2. Holders of a Canadian-issued Certificate of Identity
Do not need a visa to enter Italy for transit and or short term stay (e.g. for tourism or business purposes for up to 90 days).
It is up to the applicant to check with other relevant Schengen Countries if the above documents are accepted, even for transit purposes.