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