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