The intro (and main riff of the whole song) goes a little like this:
(just a guideline, you can use different hammer-ons/pull-offs)

   C                  F   G C        
   v       ^v^v    ^v^v v v v    ^v^v    ^v^v    ^v^v v v^v
|--0---|---0000----000------0----0000----0000----0000-0-000-----|
|--1---|o--1111----1111-1---1----1111----1111----1111-1-111----o|
|--0---|---0000----0002-2---0----0000----0000h2--2222-0-000-----|
|--0h2-|---2220h2--2223-3---0h2--2220h2--2220----0000-0-200h2---|
|--3---|o--3333----333----2-3----3333----3333----3333-3-333----o|
|------|------------------3-------------------------------------|

C                            F         G  C
Well I joined me the union a long time ago
C                                F       G  C
And now the paint in my bucket resembles my soul
C                            F          G   C
I don't paint for the union, they paint for me
C                        F       G   C
And a fine union painter I'll always be

On my way to Nevada, well I broke myself down
Here I've been stranded five years in this town
Well I heard of a place, a place I could stay
They said I'd find Jesus, and be on my way

          Am                   F           G    C           
Well they said I'd find Jesus, that's what they raved
      F           C             G          C
But I wound up in prison just before I was saved
      F           C             G          C
Yea I would up in prison just before I was saved

Well I travel the country, but I don't have a home
And I'm surrounded by others, but I'm always alone
And when the paintin' time comes, I jump back on a train
And spend all my green dollars just to poison my veins

Well they said I'd find Jesus, that's what they raved
But I wound up in prison just before I was saved
Yea I would up in prison just before I was saved

I was dead on arrival when I opened my eyes
I'm still searchin' for freedom in these southern skies
I don't paint for the union, they paint for me
      C                  F      G    C
And a fine union painter I'll always be
      F          C       G           C
Yes a fine union painter I'll always be