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