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