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