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