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