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