Change the color of a chart
Double-click the chart or click it once, then click Edit Chart on the top toolbar.
In the Data tab, click the Droplet button to change the color of the data that is being represented in the chart.
Click outside the color picker to save your new color or click the green Save button.
Note: the Droplet button from step 2 can be found to the right of your data or at the top of the data table. This depends on the kind of chart that you are using.