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