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