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