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