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