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