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