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)(27,32)(28,34)(29,35)(30,40)(31,33)(36,37)(38,39)(2,3)(6,7)(10,14)(15,17)(16,20)(23,24)(25,27,31,30)(26,32,33,40)(28,36,35,38)(29,39,34,37)(1,3,5,2)(4,7,8,6)(10,14)(11,18)(16,20)(19,21)(26,33)(28,35)(32,40)(36,38)(1,4,5,8)(2,6,3,7)(9,11,13,18)(10,15,14,17)(12,21,22,19)(16,24,20,23)(25,28,31,35)(26,34,33,29)(27,36,30,38)(32,37,40,39)(9,10)(11,17)(12,16)(13,14)(15,18)(19,24)(20,22)(21,23)(25,29,31,34)(26,35,33,28)(27,37,30,39)(32,36,40,38)(9,12,13,22)(10,16,14,20)(11,19,18,21)(15,23,17,24)(25,30,31,27)(26,32,33,40)(28,38,35,36)(29,39,34,37)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.