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