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