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