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