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