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