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