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