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