Thank you for your feedback. I understand it may feel like a missing feature, but the colour selection option was removed because it didn't serve a practical purpose and, in many cases, made the graph more difficult to interpret.
As shown in the screenshot below, when upload and download values overlap, the dominant direction is displayed in the foreground, with the lesser direction visible in the background. This allows you to clearly see both upload and download speeds for each column, even when they coincide: