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