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)(11,16)(12,17)(13,18)(14,15)(19,23)(20,21)(22,24)(25,26)(27,31)(28,38)(29,33)(30,34)(32,37)(35,39)(36,40)(1,3,5,8)(2,6,4,7)(25,27)(26,31)(28,36)(29,37)(30,35)(32,33)(34,39)(38,40)(1,2,5,4)(3,6,8,7)(10,15)(13,23)(16,21)(17,24)(27,35)(29,36)(31,39)(33,40)(1,2,5,4)(3,6,8,7)(9,11)(10,16)(12,18)(13,17)(14,20)(15,21)(19,22)(23,24)(25,28)(26,32)(27,36)(29,35)(30,37)(31,33)(34,38)(39,40)(1,2,5,4)(3,6,8,7)(9,12)(10,17)(11,19)(13,21)(14,22)(15,24)(16,23)(18,20)(25,29,30,36)(26,33,34,40)(27,37,35,28)(31,32,39,38)(1,4,5,2)(3,7,8,6)(9,13,14,23)(10,18,15,19)(11,17,20,24)(12,21,22,16)(25,26)(27,31)(28,38)(29,33)(30,34)(32,37)(35,39)(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.