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