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