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