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