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