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