Bryan Mathers of Visual Thinkery created a number of wonderful images for the book. These are all openly licensed with a CC-BY license, so like the book you are free to use them yourself as long as you acknowledge the originator (Bryan).
There is an images zip file, or select from the ones below:
Specs
Spotlight sketch
Year zero sketch
Vendors sketch
Dystopian turn sketch
Cover
Title
Alchemy sketch