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