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