This colour scheme was generated by the gecos software. See
Kunzmann, P., Mayer, B.E. & Hamacher, K. Substitution matrix based color schemes for sequence alignment visualization. BMC Bioinformatics 21, 209 (2020). https://doi.org/10.1186/s12859-020-3526-6
and https://gecos.biotite-python.org/ .
Gecos sets perceptual differences in the colour scheme according to differences in the substitution matrix.
blossom is a light color scheme with high contrast, based on BLOSUM62.
A | C | D | E |
F | G | H | I |
K | L | M | N |
P | Q | R | S |
T | V | W | Y |