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