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