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)(14,21)(17,30)(19,34)(22,37)(23,36)(24,35)(26,27)(28,33)(29,31)(32,40)(38,39) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,10)(11,17)(12,25)(13,16)(14,19)(15,18)(20,33)(21,31)(22,38)(23,28)(24,32)(26,34)(27,29)(30,36)(35,39)(37,40) involution — undirected(9,11,21,37,15,24,27,36,13,23,26,35,12,22,14,20)(10,17,31,40,18,32,29,30,16,28,34,39,25,38,19,33)(3,8)(5,7)(10,16)(17,28)(18,25)(19,29)(30,33)(31,34)(32,38)(39,40) involution — undirected(2,6)(5,7)(9,12,13,15)(10,18,16,25)(11,22,23,24)(14,26,27,21)(17,32,28,38)(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.