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