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