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