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