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