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