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