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