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