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