I think you need to change how your data is visualized. Rather than Net Working Days on the x-axis, I think you should have either Risk Print / Risk Development, or the four categories of day ranges. Then you can color the data accordingly.
When editing the chart go to Appearance => Colors and Legend. Then, turn custom colors on and select "By Expression." The expression should then just be a simple IF statement.
Here is how I think you should show this data. It may require that you rework how your data is loaded in.
This means that Dev Risk / Print Risk need to be in the same dimension. The buckets for number of completion days will have to be in a second dimension. Yes, you will not be able to show a legend. What I do is create an image which shows what the different colors mean and put it next to the chart on the sheet.