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