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