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