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