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