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