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