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