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