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