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