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