@DLane is right, as always, 
the cable you see running to the right is the power (it is wrapped in the black electrical tape). If you are interested in installing rachio in the garage you can probably pull the power cable back inside and use the original power hole to run the zone wires inside.
In case the original irrigation wires will not be long enough or thin enough in order to fit through existing hole you can pick up a 7 conductor sprinkler wire (link) at your local home improvement store. You would also need a terminal block (link) or simply a pack of wire nuts (link) as well as some enclosure to secure the outdoor junction (ask for assistance in the store to help you pick the right one out, tell them it is for irrigation).
Overall the conversion should be pretty straight forward. One thing you wish to check is the location of the indoor power socket. In case there is not one available where you wish to install Rachio, than outdoor inclosure is a good way to go (even if installing indoors).
Cheers,
Gene