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