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