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