While this discussion covers a lot about colouring and defaults in Auspice, I’ll venture a few more observations based on reading the code and experimenting.
As described in the View Settings, color_by in the auspice_config sets the key to use for colouring tips. The possible values are: almost anything mentioned in the colorings config of auspice_confg and also a few other things provided by default, most notably clade_membership (Clade), gt (Genotype) and num_date (Sampling Date).
(I say “almost anything” because in my config it seems that gisaid_epi_isl and genbank_accession are present in the list of colorings in the auspice_config but they are not selectable as colourings in the web interface)
Finally here is the list of keys my current build exposes:
clade_membership
num_date
gt
location
division
country
region
host
age
sex
author
originating_lab
submitting_lab
recency
recency
S1_mutations
mutational_fitness
logistic_growth
emerging_lineage
current_frequency
epiweek