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