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