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