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