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