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