The guitar chords are arranged in a wheel. Hold the left stick in the direction of the note you would like to play, and swipe your finger vertically across the touch pad to strum the guitar. Alternate controls for strumming the guitar are available under Options → Accessibility → Alternate Controls.
The correct note to play for story progression is identified with a white outline. Alternately, the Guitar Vibration Cues feature will vibrate the controller when the correct guitar note for story progression is selected. Guitar Vibration Cues are enabled as part of the Vision Accessibility Preset, or can be manually enabled via Options → Accessibility → Text-to-Speech and Audio Cues → Guitar Vibration Cues.
The guitar sequences can also be skipped by using the Skip Puzzle feature. It can be enabled under Options → Accessibility → Navigation and Traversal → Skip Puzzle Option.