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