Our Sparkline does not provide this functionality. I passed your inquiry to our team and we will consider this feature in the future, However, I can't provide you with any ETA.
At the moment, I recommend using one of the following workarounds:
2. Use bar charts instead of sparklines. The main idea is to create small charts and remove all labels and grids from them. This way, you will be able to specify different colors for different bars.
Let me know if you have further questions.