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