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