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