It may be tempting, in trying to show Canadian diversity, to use pictures which portray people wearing national costumes. What can happen, though, is that others who do not wear these clothes feel they are not being addressed. And pictures, also, can promote stereotypes.
Certainly it is important to show Canadian diversity, but show people wearing more generic North American clothing.
If your documents are going to be photocopied, be careful about your choice of pictures showing people who are really dark-skinned. They need to be included as representative Canadians, but you may need to adjust the darkness of the image if it becomes too dark to “read” when copied. If you do not intend to copy materials, this is not an issue.
It may sometimes be a good idea to use objects rather than people. They can be very effective and they avoid cross-cultural misunderstandings.
Test pictures as well as text with the readers you are writing for. As I said before, this is very important. People see things in different ways and what may look obvious to you may be obscure to someone else.