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