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