Z axis homes in the wrong direction, downwards

I have set the Z direction so the actual machine movement matches the axis picture.
The home switch is at the top.
I have set the home location at 0
I have set travel from -70 to 0
When I attempt to home the Z axis it moves downwards (away from the home switch).

How do I fix this please?

Not only easy but a fix too!
Thanks, all working now.

I scratched my head on this one for over an hour, figured I did something wrong. So double thanks for the answer. BUT, someone should put this into the guide somewhere. It would seem to me that this is a common thing, especially on the Z Axis.