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)(25,26,31,33)(27,32,36,28)(29,38,37,34)(30,35,39,40)(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)(28,33)(29,39)(30,37)(31,36)(34,35)(38,40)(2,5)(6,8)(10,16)(13,18)(17,20)(22,24)(26,33)(27,36)(29,37)(35,40) involution — undirected(3,7)(6,8)(9,12,15,23)(10,17,16,20)(11,19,14,21)(13,22,18,24)(25,28)(26,27)(29,35)(30,34)(31,32)(33,36)(37,40)(38,39)(1,2)(3,6)(4,5)(7,8)(9,13)(10,11)(12,22)(14,16)(15,18)(17,19)(20,21)(23,24)(25,29,31,37)(26,34,33,38)(27,30,36,39)(28,35,32,40)(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)(26,35)(27,37)(28,38)(29,36)(31,39)(32,34)(33,40)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.