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