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