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