I 've searched the web for that diagram with no satisfactory result. Does a schottky diode has capacitance or not because of very tiny depletion (almost none) zone ?
Capacitance – Voltage characteristic diagram in a Schottky diode
Schottky diodes have pretty constant reverse capacitance with reverse voltage changes. There is usually only about a 2:1 change in C with quite large changes in Vr. I've used a BAT41 recently and this is the graph: -
I would also suggest that most commonly used schottky diodes do possess this graph in their respective data sheets so if you have one particular device in mind take a look.
EDIT - I just took a look at a few devices on Farnell and every device's data sheet had a graph of capacitance vs reverse voltage.