One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7,6,3,4,8)(9,10)(11,17)(12,20)(13,15)(14,18)(16,22)(19,24)(21,23)(26,31,33,37)(32,38,40,39)(1,3,6,2)(4,7,5,8)(9,11,13,19)(10,14,15,23)(12,21,22,18)(16,24,20,17)(25,26)(27,32)(28,31)(29,37)(30,33)(34,39)(35,40)(36,38)(2,3)(7,8)(10,15)(14,23)(16,20)(17,24)(25,27,30,35)(26,32,33,40)(28,36,29,34)(31,38,37,39)(25,28,30,29)(26,31,33,37)(27,34,35,36)(32,39,40,38)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.