Can I substitute canola or safflower oil for vegetable oil when making granola?

canola oil and vegetable oil are the usually the same thing. Veg oil is simply a less specific oil that could be made from different or combined vegetable sources, but not those which contain nut oils.

sunflower (not safflower) oil is likely your best bet for the least flavor contribution to your granola.

"vegetable oil" is a catchall term for "we put in the bottle a blend of whatever neutral, somewhat heat stable edible oils we had a surplus of". This can be corn, canola, soy, (probably not peanut because of allergy risks), (probably not light olive oil), refined safflower, sunflower and other.

At least corn, soy, REFINED canola/rapeseed, REFINED safflower, sunflower will be safe substitutes. Be careful with "cold pressed"/"unrefined" versions, these are meant for a different purpose and do not meet the heat stability expectations a recipe specifying "vegetable oil" could have.

It is made from canola plants, but works just the same. I regularly substitute Canola oil for vegetable oil in recipes and do not notice the difference. It is healthier, has a similar burn point, and has no odor so it is a good choice.