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