the problem with geolocation is that it is not systematically enabled on all browsers. You have check with your own javascript code to test if your visitor’s browser has it.
If you do get a location coord to initialise the map, then you would need to setup a new marker and a new centre.
Currenlty there ins’t an easy way to achieve this, I can add this in a future release.
If you have some javascript skills, you can interact with your map once it is initialised. The plugin uses the Gmap3 js plugin, which has a method to retrieve the google map object,
$('#cf7-googlemap-<field-name>').gmap3().get(0)
where <field-name>
is the name of the field containing the map in your form.