Riff 1

e|---------------------------------
b|---------------------------------
g|---------------------------------
d|---------------------------------
a|3-333-333-33/9-99-3-333-336-5-4--
E|1-111-111-11/7-77-1-111-114-3-2--

Riff 2

e|---------------------------------
b|---------------------------------
g|---------------------------------
d|----------------------3-3-3-3-3--
a|2-2-2-2-2-3-3-2-2-2-2-1-1-1-1-1--
E|0-0-0-0-0-1-1-0-0-0-0------------

Riff 3

e|---------------------------------
b|---------------------------------
g|---------------------------------
d|------------------------3-333-33-
a|2-222-222-2223222-222-221-111-11-
E|0-000-000-0001000-000-00---------

Riff 4 - a bit of variation with the palm muting on this riff

e|---------------------------------
b|---------------------------------
g|---------------------------------
d|---------------------------------
a|3--3-3-3-3/9-9-3--3-36-5-4-6-5-4-
E|1--1-1-1-1/7-7-1--1-14-3-2-4-3-2-

finito