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