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