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