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