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