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