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