The control should clearly tell the user where to click / swipe and what the result will be.
Take these iOS switches for example:
Side by side, a user can easily see which setting is activated and which is deactivated. However, if you observe how users interact with them (especially if they are all in the same state or only one exists), you will find them pausing to consider how to change the setting.
Apple deliberately preferred the style of usability (similar to the invisible scroll bars of Mac OS). Once you've learned it, control is obvious, but the beginner has to pause.
If you embed the "value" directly in the control, you are giving a style in the name of clarity. This is less sexy than the iOS example, but the user will understand at a glance what is expected.
In the following example, I reversed the most common position (
on right), but nobody will be confused.
I also used a common "positive" color for on. Your use of red for breaks with conventions in a way that can further confuse the user.
* UPDATE * In response to the commentators' observations, I took a second look at my short mock. I think this does a better job of showing the condition. Thanks for the criticism!
Another purely anecdotal finding from me: position the setting label on the left and the control element on the right. This enables the user to scan the label before worrying about the status of the control.