This only changed it for chart titles, but left axis titles the default color:
import matplotlib as mpl
mpl.rcParams['text.color'] = 'blue'
You can set each text property separately, e.g.:
COLOR = 'blue'
mpl.rcParams['text.color'] = COLOR
mpl.rcParams['axes.labelcolor'] = COLOR
mpl.rcParams['xtick.color'] = COLOR
mpl.rcParams['ytick.color'] = COLOR
The full list of params is at https://matplotlib.org/users/customizing.html.
To set the label color in the rcParams as well use
text.color: blue
axes.labelcolor: blue
or, from within the script
mpl.rcParams.update({'text.color' : "blue",
'axes.labelcolor' : "blue"})