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)(11,15)(12,19)(13,22)(14,17)(16,18)(20,24)(21,23)(25,26,28,31,29,32,35,38)(27,30,34,37,33,36,39,40)(1,3)(2,5)(4,8)(6,7)(9,11,14,13)(10,15,17,22)(12,20,21,18)(16,19,24,23)(3,8)(5,7)(9,12,14,21)(10,16,17,24)(11,18,13,20)(15,23,22,19)(25,27)(26,30)(28,34)(29,33)(31,37)(32,36)(35,39)(38,40)(2,6)(5,7)(27,33)(30,36)(34,39)(37,40) 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.