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