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