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)(11,16)(12,17)(13,26)(14,18)(15,22)(19,29)(20,32)(21,33)(23,40)(24,37)(25,35)(27,31)(28,36)(30,39)(34,38)(9,11,14,21)(10,15,18,31)(12,23,25,39)(13,27,29,22)(16,19,33,26)(17,34,35,32)(20,28,38,24)(30,37,40,36)(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)(5,7,8,6)(10,18)(11,21)(17,35)(19,26)(20,38)(22,27)(23,39)(36,37)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.