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