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