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