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