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