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