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