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