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