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