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