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