For obtaining the above image I used this xyz file in which different 'types' of spins appear ('Sc', 'Sp', 'd' etc).
After opening the Set Spins dialog box, I selected 'Sc' at the Type field (as shown below), then determined the color and size properties and pressed on Apply. I repeated this step for all the different 'types'.
The coloring definition is according to the z - component of the spins.
The coloring definition is a color gradient along the y axis.