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