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