Why not make your own coffee roast color guide?
Here are some images of “degree of roast” sets that I made. The boxes are a clear type used for displaying beads and other craft objects. I bought these from The Container Store as I recall.
The roast samples represent the Degree of Roast simply means the roast level of a coffee, how dark it has been roasted.: Degree of Roast simply means the roast level of a coffee,... ...more levels from green to Full City+ roast is an ideal roast level that occurs roughly between 425 and 435 degrees Fahrenheit in many coffee roasters with a responsive bean probe where First Crack... ...more. I skip some of the yellowing and browning stages, focusing on the levels starting just before First crack in one of two distinct heat-induced pyrolytic reactions in coffee. It is distinguished by a cracking or popping sound in the coffee, and occurs between 390... ...more, City roast is what we define as the earliest palatable stage that the roast process can be stopped and result in good quality coffee. City roast occurs roughly... ...more, City+, A coffee that has been roasted to the brink of second crack.: A coffee that has been roasted to the brink of second crack. The internal bean temperature... ...more, and then a bit into After First Crack, a roast reaction around 440 to 450 degrees that is distinguished by a snapping sound. Second Crack is the second audible clue the roaster-operator receives... ...more territory.
The set on the left dedicates one row to washed (wet-process) Green coffee refers to the processed seed of the coffee tree fruit. Coffee is a flowering shrub that produces fruit. The seeds of the fruit are processed, roasted,... ...more and the other to decaf, since decaf roast color can be so hard to gauge.
The set on the right also has wet-process coffee, compared alongside natural (dry-process) coffee. Each stage is the roast time and temperature equivalent. You can see how perceived color varies though.
Other roast and green coffee-related reading: