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)(27,33)(28,36)(29,32)(30,35)(31,37)(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)(25,27,29,35)(26,30,32,33)(28,34,37,40)(31,38,36,39)(10,15)(12,21)(16,23)(18,24)(25,26,29,32)(27,33,35,30)(28,31,37,36)(34,39,40,38)(1,3,5,4)(2,7,6,8)(9,11,14,19)(10,16,15,23)(12,18,21,24)(13,17,22,20)(25,26)(27,30)(28,31)(29,32)(33,35)(34,38)(36,37)(39,40)(1,3,5,4)(2,7,6,8)(9,12,14,21)(10,17,15,20)(11,18,19,24)(13,16,22,23)(25,27)(26,30)(28,34)(29,35)(31,38)(32,33)(36,39)(37,40)(1,4,5,3)(2,8,6,7)(9,13,14,22)(10,18,15,24)(11,17,19,20)(12,16,21,23)(25,28,29,37)(26,31,32,36)(27,34,35,40)(30,38,33,39)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.