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