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