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