Here's a picture from one of my kindergarten classes when I was an art teacher. The dozen or so kids visible are working on a great big thank you banner for the fire station they just visited. (I drew it and they colored, following guidelines from our lesson in color theory.) As you can see, they're all engaged and working hard to see the finished picture!
Large-scale graphic recording has the same effect on grown ups. It gets them engaged (even thought they're just watching) and keeps them engaged in the content. Even when minds wander, the subtle movement of the graphic recorder and the curiosity of what the finished picture will look like draw them right back to the content - just where you want the focus to be!