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