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