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