To set Different Colors For each column in Column Chart

[yazh21]

I have code to Generate Excel File where with my data on excel sheet , it creates Column Chart using Npoi package. In that I have 4 columns in my column chart where all columns color is blue by default. I want to set custom colors for each Column in Column chart that is 4 different colors for 4 columns in column chart.How to Achieve this?
This is Sample for Column Chart Generated
This is Sample for Column Chart Wanted