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