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