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