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