Greetings from Syncfusion.
We have analyzed your query and your requirement can be achieved using two ways.
If the data are declared directly in points, then you can directly use the fill property to assign the desired color. Find the code snippet below.
<ej:points Text="Insignificant" X="Insignificant" Y="10" Fill="green" />
If you are bind data to chart using the data source, and you are having color in your data source, then using the pointColorMappingName in series. Find the code snippet below to achieve this requirement.
Hope this helps.