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