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