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