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