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