Creation of PDFs gets colors of graphs wrong

[luciansmith]

plot_2_task2.pdf
from https://biosimulations.org/runs/674e56e9f643f14403cba8aa#tab=metadata

and
plot_2_task2.pdf
from https://biosimulations.org/runs/674e5f31dc9881557032f04f

The legend colors are different from the actual plot's colors.

Thanks to @stellaprins for noticing this.