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