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