Riff A:

E|-----0-----0-----0-----0--|
B|---4-----4-----4-----4----|
G|-4-----3-----2-----1------| Repeat 8 times
D|--------------------------|
A|--------------------------|
E|--------------------------|


Riff B:

E|----4---4---4---4-2----4---4---4---2-------|
B|-2----2---2---2-----5----2---2---5---5-5-4-|
G|-------------------------------------------|
D|-------------------------------------------|
A|-------------------------------------------|
E|-------------------------------------------|


E|-----------------------------------0-4--|
B|-2-----0-------------2-0---0---2-4------|
G|---1-----3-1-3---1-3-----3--------------|
D|-----2---------4------------------------|
A|----------------------------------------|
E|----------------------------------------|


The playing order is

Riff A
Riff B
Riff A
Riff B x2
Riff A
Riff B x2
2nd half of B
(some single tones)