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