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