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