Riff 1 
G----------------------------------------------------------
D----------------------------------------------------------
A-----------------------4----------------------------------
E---222455555555--45---------------------------------------

Riff 2
G----------------------------------------------------------
D----------------------------------------------------------
A-----------------------5544-------------------------------
E---5555555------222---------------------------------------

Riff 3 
G----------------------------------------------------------
D----------------------------------------------------------
A----------------------------------------------------------
E---55555555555---444444-----22222222----------------------

Riff 4
G------------------------------------------------------------
D------------------------------------------------------------
A--------------444--5----------------------------------------
E---222--45------------0-------------------------------------

And the order is : 
Riff 1x3
Riff 2x8
Riff 3x2
Riff 2x8
Riff 3x4
Riff 4x4
Riff 3x4