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