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