When colours are next to each other it is simple to tell the difference between two blues or shades or red and orange however as soon as they are separated or only one example is shown on the page it can be much harder to tell the difference.
In the course of producing many summary plans I have found the web page below extremely useful especially if a member of the team or recipient of the Plan on a Page has some issues distinguishing between colours.
A list of 20 simple, distinct colours
The basic list of 20 colours (below) is refined by selecting the level of accessibility.
Use the RGB settings to allow you to select the colour to be applied to bars, milestones and swim-lanes in SummaryPro and have the same settings applied to the key etc.