Colour is an important consideration in design. Use colour carefully, it should reinforce the main messages in your data.
Do not rely on colour alone to communicate the stories in your data. The important messages communicated by the data must be clear if the graphic is viewed in black and white or if the user is colour-blind.
When considering your colour choices look at the relationships present in the data. It should be used to group related items and command attention. Contrasting colours can be used to focus attention on differences, or interesting areas, within the data.
A safe starting point is to use subdued, pastel colours or greyscale to communicate the majority of your information.