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