For those who would rather have a map of the twelve locations than a video, there's this one (click for full size):
The drawings are all the same, and look like this:
Simply stand in front of each drawing and press
when prompted. Most, but not all, are on ground level. For those interested, the drawings are the product of Sunset Overdrive Game Director Drew Murray's 4-year old daughter Ainsley. D’awwwwww!
I have also confirmed that there is no map for these available for purchase in-game from Jack.
Map and drawing image both courtesy of the Developer.
Edit: Per Dylan XBA
, if you have an issue whereby not all drawings register (tracker showing 83% despite having found all 12 drawings), you can go offline, delete local save data, start a new game and get all the drawings before going back online, getting the achievement and then deleting the local save data again before syncing with the cloud data.