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