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