If you choose similar colors for Reactions you may want to use different colors for Charts.

Navigate to Reactions > General Settings.
In this page there is a setting that lets you choose between three different options:
- Use the same colors as Reactions: This is the default value and renders the Charts with the same colors you chose in Reactions Settings Page;
- Use random generated colors: Generates RGB values from reactions labels, so identical labels will have identical colors;
- Use default rainbow palette: Uses a default palette with 20 different tints, use this if the previous options does not work for you.