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