To define colors to change according to a target, you need to go to Chart properties --> Visual Cues --> Select the expression and specify your target in Upper and/or Lower. Select your color appropriately.
However, this probably only works for a straight table and a pivot table. Is that what you are looking for?
In addition to the solution provided by khaled, you can also change the color in the expression tab by adding the condition like
if (Target <0,red(), if(target >0 and target <50 , rgb(100,132,143),rgb(222,65,66)))
You need to add the condition in the defination tab on right.
Attach is the screen shot for the same.
01.jpg 108.3 K