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