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