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