Is there a documented Rubin style guide anywhere? Specifically, are there set hex colour codes for each filter we can use for plotting Rubin lightcurves?
You are likely looking for these:
from lsst.utils.plotting import get_multiband_plot_colors, get_multiband_plot_symbols
filter_colors = get_multiband_plot_colors()
filter_symbols = get_multiband_plot_symbols()
The 306_1 notebook (between others) of the DP1 tutorial series contains an usage example.