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