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