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