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