First note that you are not using SSL-level compression, but HTTP-level compression: there is a HTTP header which describes the mode of compression. The compression is applied to the HTTP response body only, i.e. the
colors.min.js file, at the exclusion of anything else, in particular HTTP cookies or other such values.
Compression is unsafe when applied on secret values and the attacker has the possibility to get many examples of compressed data with the same secret repeated in all of them, but also with variants. In particular when the attacker gets to insert data chosen by him within the data sequence that is compressed.
Even if the compressed data was not public, a static file could still be served with compression, because compression is deterministic and would yield the exact same sequence of bytes every time, so, in particular, always the same length -- nothing to learn for the attacker.