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