I've been wondering about how some of the colours were arrived at and certainly, some of the animals associated with various sins do not seem apropos. Why, for instance, would the colour for greed be yellow and why the frog as its animal. Stranger yet, why would the punishment be cauldrons of boiling water. Seems red and lobster might be a better choice.
Looking at the various punishments, the challenge of demonstrating these is enormous and leads me to consider other options.
Here are the punishment according to sources on Google:
Pride, on the breaking wheel or Catherine Wheel as seen in this Cambridge College coat of arms (Catherine College)
Envy, immersed in freezing water
Gluttony, eat rats, toads and snakes.
Greed, put in cauldrons of boiling oil.
Lust, smothered in fire and brimstone.
Sloth, put in a snake pit.
I wonder if they mean a snake pit like the one below.