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