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