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