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