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