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