Intro:
G--------7---------7--------------------------------------------
D-9-8-9----9-8-9------5-7-5-7-5--------5---5-7-----------------
A---------------------------------7-5-7---7---------------------
E----------------------------------------------------------------

Main Riff(Played after into up until the corus):
G----------------------------------------------------------------
D------7------5---5-7--------------------------------------------
A---------5h7---7------------------------------------------------
E-5-5------------------------------------------------------------

This is a line u can alternate in for the main riff to change it up a bit:
G----------------------------------------------------------------
D-----7---------7-5----------------------------------------------
A---------5-7-------7-5------------------------------------------
E-5-5-------------------------------------------------------------

This is another alternate line you can substitute in for the main riff:
G----------------------------------------------------------------
D-----7------5---5-5h7-------------------------------------------
A-------5h7----7-------------------------------------------------
E-5---------------------------------------------------------------

During the chorus you can just play notes along with the lyrics thats whats 
Phil Lesh (bassist for the dead) does.

This is what I play during the chorus:

G---------------5-6-8-6-5-4------66-6-66--------------------------------
D--7-7-5-7-5-7---------------5=-----------12-13-15-13-12-11-10-9-8-7--
A------------------------------------------------------------------------
E-------------------------------------------------------------------------

After the very last note of the chorus go back and play the intro riff then 
jam on the main line and go into the 2nd verse.