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