How to turn off data roaming in iOS 7?
You enable Data Roaming when showing the green part to the left.

On iOS 6 and older you had the text ON or OFF on the button. OFF disabled Data Roaming, and ON enabled Data Roaming and the button was showing a blue background behind the ON. So on iOS 7 you have the same behavior - just without the ON/OFF text, and with a green background - you can however turn on an 1 as ON and a 0 as OFF under Settings=&gt;General=&gt;Accessibility=&gt;On/Off Labels)