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