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