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