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