pull measure on the mark shelf (Color), select Red Green Diverging or Custom Diverging. Stepped Color=2 Steps
You can change color in custom diverging option
You're in right direction to achieve that.
Just create your positive and negative measures separately then custom format your negative measure like that.
Use ABS() function outside your negative measure to convert in absolute number.
Then drag your positive and negative measures to label and edit the labels to align and color only negative measures
As per your screens shot you can choose the color banding of rows and color of the sheet.
workbook version 9.3 attached for your reference. Let us know If you've any query.