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