One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10,15,18,14,19,13,20)(11,21,22,24,12,16,23,17)(25,26,29,33,28,32,38,31)(27,34,37,40,36,30,35,39)(2,5)(6,7)(9,11)(10,16)(12,14)(13,23)(15,22)(17,18)(19,21)(20,24)(25,27,29,37,28,36,38,35)(26,30,33,39,32,34,31,40)(9,12,14,11)(10,17,19,24)(13,23,15,22)(16,20,21,18)(26,31)(27,35)(29,38)(30,34)(32,33)(36,37)(1,3,4,8)(2,6,5,7)(9,13,14,15)(10,18,19,20)(11,22,12,23)(16,24,21,17)(26,32)(27,36)(31,33)(35,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.