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