for me your code snippet looks already quite good. Maybe only the pen color (color of the line) is missing, i.e. you have to change
or any other color you want.
I completed your code snippet to a full script:
import numpy as np
fig = pygmt.Figure()
region=[0, 10, -10,10],
# pen="1.5p", # <<< maybe color of basic line is missing?
There is further a PyGMT gallery example explaining how to draw Line fronts — PyGMT.
For a more detailed help, please post your own complete script .