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)(11,16)(12,15)(13,17)(14,18)(19,20)(21,23)(22,24)(26,30)(28,35)(31,36)(34,39) involution — undirected(2,5)(6,7)(9,11)(10,13)(12,19)(14,17)(15,22)(16,18)(20,23)(21,24)(27,33)(31,36)(34,39)(38,40) involution — undirected(1,2)(3,6)(4,5)(7,8)(25,26)(27,31)(28,32)(29,30)(33,36)(34,38)(35,37)(39,40) involution — undirected(1,3)(2,6)(4,8)(5,7)(9,12,14,21)(10,15,18,23)(11,19,17,24)(13,22,16,20)(25,27)(26,31)(28,34)(29,33)(30,36)(32,38)(35,39)(37,40)(9,11)(10,16)(12,19)(13,18)(14,17)(15,20)(21,24)(22,23)(25,28,29,35)(26,32,30,37)(27,34,33,39)(31,38,36,40)(9,13,14,16)(10,17,18,11)(12,20,21,22)(15,19,23,24)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.