It really depends on what the magic does, and whether it’s supposed to have any visible side-effects or not.
If it is supposed to have some visible glowy effects, then you can render those, but I tend to prefer not to want to show magic as “light powers”, as that’s been overdone and does often seem cartoony to me.
Another style is to add subtle outlines of the magic at work, that aren’t supposed to actually be visible, but make the image into a kind of diagram of what’s happening.
Another style is the “halo of arcane symbols” type of thing, which some medieval/Rennaissance Christian artists went in for.
Another style is to not show anything other than the effects, intent and reactions in the gestures and expressions of the people in the scene.