Like some of the other riffs in this song, we'll be palm muting the Low E string notes, while all other notes are played normally without palm muting.
Also, if you want, some of the picking in this riff can be played a little differently than how I indicated in the tab. For example, there are some upstrokes that you might rather play as a downstroke etc., and that's fine. However, one thing that you for sure need to keep consistent is the alternate picking during the fast palm-muted parts.