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