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