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