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