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