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