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