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