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