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