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)(11,14)(12,16)(13,17)(15,18)(19,21)(20,23)(22,24)(25,26,31,35)(27,36,39,32)(28,29,40,33)(30,34,38,37)(1,2)(3,5)(4,6)(7,8)(9,11)(10,14)(12,19)(13,18)(15,17)(16,21)(20,24)(22,23)(25,27,31,39)(26,32,35,36)(28,37,40,34)(29,38,33,30)(11,18)(12,20)(14,15)(16,23)(25,28,31,40)(26,33,35,29)(27,37,39,34)(30,36,38,32)(9,11)(10,15)(12,19)(13,18)(14,17)(16,22)(20,24)(21,23)(25,28)(26,29)(27,37)(30,36)(31,40)(32,38)(33,35)(34,39) involution — undirected(9,12,13,20)(10,16,17,23)(11,19,18,24)(14,21,15,22)(25,29)(26,28)(27,38)(30,39)(31,33)(32,37)(34,36)(35,40)(1,3,4,7)(2,5,6,8)(9,10)(11,15)(12,16)(13,17)(14,18)(19,22)(20,23)(21,24)(25,30,31,38)(26,34,35,37)(27,29,39,33)(28,36,40,32)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.