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