Hi Jeffrey - it looks like this may be a bug, as the downloaded image should be using your chosen colour for the the route. We'll look into that. For better stannd-out though, I'd recommend reducing your line transparency setting.
I have set my route display color to be red and the line transparency to be 35%. However, when I download the map as jpg, gif, or png, the color of the route is blue and the thickness of the line is narrow. Is there a way to change the color of the route to stand out more from the map background and increase the thickness of the route line?