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