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