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