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