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