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