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