Right click on the chart and choose Format
Then, a format menu sidebar will appear on the right.
You can choose from the list of data series.
Depending on which series you need to modify color, choose that series.
As an example, if I want to change the default blue color on the column chart, choose the Measure series.
Then, you can change the fill color to a color of your choice.
Similarly, each series (threshold, above threshold, min, max, custom hightlight, Pareto) can be changed.