This song just gets to me every time I hear it, so I set out tonight to learn it myself.
chords on the version I found here were perfect, but playing solo they were a little
therefore I figured out an easy little finger picking melody that seemed to fit nicely 
playing/singing without a band in the background. So, here goes-

Capo 4 - Chords D2, Am7, C2, G

D2 (x43141@2)             Am7 (x02010@1)             C2 (x32030@1)             Ge-----0-------0--------0-------0---------3-------3--------3-------3----| (320003@1)b--3---3-3-3---3-3--1---1-1-1---1--1--3---3-3-3---3-3--3---3-3-3---3-3-|
g---2---2---2---2----0---0---0---0-----0---0---0---0----0---0---0---0--|
d-0--0----0--0--------2-------2---------0-------0--------0-------0-----|
a------------------0-------0---------3-------3-------------------------|
d-----------------------------------------------------3-------3--------|
(Just listen to the rhythm of the song and the pattern won't be hard to pick up)

D2 (x43141@2)           Am7Worthy (x02010@1)is the, Lamb who was slain
C2 (x32030@1)           GHoly, (320003@1)Holy, is He
D2 (x43141@2)             Am7Sing (x02010@1)a new song, to Him who sits on
C2 (x32030@1)           GHeaven's (320003@1)Mercy Seat
[Repeat 2x]

(Chorus- Strum this)
D2Holy, (x43141@2)Holy, Holy
Am7Is (x02010@1)the Lord God Almighty
C2 (x32030@1)                       GWho (320003@1)was, and is, and is to come
D2With (x43141@2)all creation I sing:
Am7Praise (x02010@1)to the King of Kings!
C2You (x32030@1)are my everything,
GAnd (320003@1)I will adore You

(Verse 2- Fingerpick)
Clothed in rainbows, of living color
Flashes of lightning, rolls of thunder
Blessing and honor, strength and
Glory and power be
To You the Only Wise King,
Yeah

(Chorus- Strum)

(Verse 3- FP)
Filled with wonder,
Awestruck wonder
At the mention of Your Name
Jesus, Your Name is Power
Breath, and Living Water
Such a marvelous mystery

(Chorusx2- Second time with light strumming and end)

Hope you enjoy playing this as much as I do =)
Good Luck and God Bless
-James