THIS IS HOW I THINK IT IS PLAYED. THERE ARE ONLY 4 RIFFS, SO HERE THEY ARE.
P.M.= PALM MUTE
RIFF 1
E|-------------------|E
B|-------------------|B
G|--------------0----|G
D|-----0-------------|D
A|---8---8---8----8--|A
E|-9-------9---------|E
P.M. P.M.
RIFF 2
E|---------------------------------|E
B|---------------------------------|B
G|-----0-------0-------0-------0---|G
D|---0---0---0---0---0---0---0---0-|D
A|---------------------------------|A
E|-6-------6-------5-------4-------|E
RIFF 3
E|--------------------------------|E
B|--------------------------------|B
G|-7-7-7-6----6--6--6--7-7-7-6----|G
D|-7-7-7-6----6--6--6--7-7-7-6--5-|D
A|-5-5-5-4----4--4--4--5-5-5-4--5-|A
E|------------------------------3-|E
RIFF4
E|------------------------------------------------------------------------------
B|------------------------------------------------------------------------------
G|-7-7-7-6----6--6--6--7-7-7-6--------------------------------------------------
D|-7-7-7-6----6--6--6--7-7-7-6--------------------------------------------------
A|-5-5-5-4----4--4--4--5-5-5-4--------------------------------------------------
E|------------------------------3-3-3-3-3-3-3-3--2-2-2-2-2-2-2-2--1-1-1-1-1-1-1-
REST OF RIFF 4
E|-------------------|E
B|-------------------|B
G|-------------------|G
D|-------------------|D
A|-1-1-1-1-1-1-1-1-1-|A
E|-------------------|E