Unfortunately, it is not possible to manually back up game data to iCloud or any third-party backup applications. Please use Facebook or Apple ID to save your game data and synchronize it between devices.
By default, the option to load cloud saves is turned on automatically. You can turn this setting off or choose which save you would like to load by turning on the ‘Cloud Load Confirm’ tick box.
You can find this box by navigating through the bottom left menu on the map and selecting the cogwheel to open the Game Settings Menu. On the first page of the settings menu, you will notice two small pips at the bottom. Tap the second pip to access the second settings screen to find the cloud save options.