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