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