You should be able to change the color of your bars on a bar graph. Like on Excel Online, you can't change your bars different colors.
We’re happy to announce that we’re currently rolling out a format task pane for charts. This enables many formatting actions including color formatting of data series.
Once the update reaches you, it can be accessed through the “Format” button, found by right-clicking on a chart or by selecting a chart and navigating to the “Chart” tab that appears in the ribbon at the top of the screen. Thank you for your continued feedback and responses.
Thank you for your continued feedback and responses.
In the online version of Excel it isn't possible to change the colour of bars in charts or graphs on the chart menu. You can't right-click to change them either. I use charts a lot in my work and need to be able to change the colours as easily as I can in the desktop version of Excel