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