The Night Shift toggle has been removed from Control Center in iOS 11 (Public Beta 1). There is also no option to add a Night Shift toggle in the Control Center customization settings. To manually enable or disable Night Shift you now have to navigate to Settings > Display & Brightness > Night Shift. From here tap the "Manually Enable Until Tomorrow" to enable Night Shift on your device.
How do I enable/disable Night Shift mode in iOS 11 or later?