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