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