Cream only lasted two years but they kicked out their fair share of great riffs in this time. The Sunshine of Your Love was written by bassist Jack Bruce after seeing Jimi Hendrix (who would later cover the song).
The first part of the riff is single notes and the second introduces 7th chords for some of the notes. You could just continue to use single notes as before if you prefer.
A few of the notes call for vibrato. You can create these in a couple of ways. You can bend the string (pull it down or push it up) and release the string a few times. Alternatively, you can wiggle your fretting finger along the neck (but staying within the fret). This is the method I prefer for the uke – it’s more subtle and easy to control.
Suggested by weelie