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)(11,14)(12,16)(13,17)(15,18)(19,22)(20,21)(23,24)(25,26)(27,31)(28,33)(29,34)(30,32)(35,39)(36,38)(37,40)(1,3,5,8)(2,6,4,7)(9,11)(10,14)(12,19)(13,18)(15,17)(16,22)(20,23)(21,24)(25,27,30,36)(26,31,32,38)(28,29,35,37)(33,34,39,40)(1,2,5,4)(3,6,8,7)(11,18)(14,15)(19,24)(22,23)(26,32)(31,38)(33,39)(34,40)(9,10)(11,14)(12,20)(13,17)(15,18)(16,21)(19,23)(22,24)(25,28)(26,33)(27,29)(30,35)(31,34)(32,39)(36,37)(38,40) involution — undirected(9,11)(10,15)(12,19)(13,18)(14,17)(16,23)(20,22)(21,24)(25,29)(26,34)(27,35)(28,36)(30,37)(31,39)(32,40)(33,38) involution — undirected(1,4,5,2)(3,7,8,6)(9,12)(10,16)(11,19)(13,21)(14,22)(15,23)(17,20)(18,24)(25,26)(27,31)(28,33)(29,34)(30,32)(35,39)(36,38)(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.