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