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)(13,21)(14,17)(15,19)(20,23)(22,24)(25,26)(27,31)(28,33)(29,32)(30,34)(35,38)(36,40)(37,39)(1,3,4,8)(2,5,6,7)(25,27)(26,31)(28,36)(29,35)(30,37)(32,38)(33,40)(34,39)(9,11)(10,15)(12,19)(13,22)(14,20)(16,23)(17,24)(18,21)(26,32)(27,35)(28,29)(33,34)(36,37)(38,40) involution — undirected(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,24,18)(25,28,30,29)(26,33,34,32)(27,35,37,36)(31,38,39,40)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.