Having more than one color for a series is unnatural and it is not supported by our chart. It might be confusing for clients that are not used to it. If you however insist of using this approach I would recommend the approach that Victor has suggested - simply use more series. This will make it easier on you when describing them in the legend if you use one.
In theory you might be able to override the class that renders the bars, but I am not sure what the result might be, as I said, this is going outside of our designs.
You might consider purchasing a license as suggested by Victor. This will entitle you to our dedicated support where me and my team will be able to help you further with overriding and extending our controls and integrating them for your project needs.
Thank you for your time and all best!
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