Hi!
The color scale depends on the assigned Maximum and Minimum speeds. It is a comparative allocation.
In case "X / Y Movement speed" is higher than "Default printing speed" you will see this as the maximum value of the scale.
-If for example you set 80mm / s for "Default printing speed" and 10mm / s for "X / Y Movement speed" you will see that the model layers will be yellow and red.
-if you set 80mm / s for "Default printing speed" and 200mm / s for "X / Y Movement speed" the layers of the model will have a green tendency because compared to 200mm / s the printing speed is much lower.
Cheers!