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