Your scenario sounds like you have few series (clusters) and the bars of each series is placed in a different category slot. Can you confirm this is your scenario? If so, I can suggest you to take a look at the Dynamic Number of Series
help article. Basically you can have a collection with view models for your series (clusters) and each series will have a collection of data points. To ensure each cluster will be in different category slot (the length between two adjacent ticks on the axis) you can set the property which is bound to the CategoryBinding of the BarSeries. For example, all items in "cluster1" will have a single category, all items in "cluster2' will have another category, etc.
As for the coloring of the bars, by default when you set a Palette
for the chart, each series will be colored with a different brush. If you want to alter this behavior (each data point to be different color) you can set the PaletteMode property of the BarSeries to DataPoint. The default value is Series. For example, if the PaletteMode is set to Series and you have two series, all items in the first one will be one color and the items in the other one will be another color. Otherwise (PaletteMode set to DataPoint) each data point will be different color. Note that this property will be applied only if you set a Palette on the chart.
For your convenience I attached a sample project that demonstrates this approach.
Please let me know if I am missing something.
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