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)(25,26,30,29)(27,31,35,33)(28,36,38,32)(34,40,37,39)(1,2,4,5)(3,6,7,8)(9,11,15,13)(10,16,17,19)(12,22,23,20)(14,21,18,24)(25,26,30,29)(27,33,35,31)(28,32,38,36)(34,40,37,39)(1,2)(3,6)(4,5)(7,8)(10,17)(14,18)(16,19)(21,24)(26,29)(31,33)(32,36)(39,40) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,12)(10,18)(11,20)(13,22)(14,17)(15,23)(16,21)(19,24)(25,27,30,35)(26,31,29,33)(28,37,38,34)(32,40,36,39)(1,3,4,7)(2,6,5,8)(9,13,15,11)(10,19,17,16)(12,20,23,22)(14,24,18,21)(25,28)(26,32)(27,34)(29,36)(30,38)(31,39)(33,40)(35,37)(9,14,15,18)(10,12,17,23)(11,21,13,24)(16,22,19,20)(25,29,30,26)(27,33,35,31)(28,36,38,32)(34,40,37,39)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.