According to the description, the color for origin and axis labels should default to color. However,

• if origin color is defined without a frame label, then origin color is ignored
• if a frame label is given, then the color is set to blue for origin and axis labels

X = SE3.Rand()
X.plot(color=["r","g","b"], textcolor="k", origincolor="k", style="line")

X.plot(frame="A", color=["r","g","b"], textcolor="k", origincolor="k", style="line")

There was some "code duplication".