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