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