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