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