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