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