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