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