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