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