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)(11,15)(12,14)(13,20)(16,21)(17,18)(19,24)(22,23)(28,36)(31,38)(34,40)(37,39)(1,3,5,8)(2,6,4,7)(9,10,14,12)(11,15,17,18)(13,16,21,20)(19,22,23,24)(25,26,29,32)(27,30,35,33)(28,31,36,38)(34,37,40,39)(10,12)(11,17)(16,20)(19,23)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,38)(37,40) involution — undirected(9,11,14,17)(10,15,12,18)(13,19,21,23)(16,22,20,24)(1,4,5,2)(3,7,8,6)(9,12,14,10)(11,18,17,15)(13,20,21,16)(19,24,23,22)(25,27)(26,30)(28,34)(29,35)(31,37)(32,33)(36,40)(38,39)(9,13,14,21)(10,16,12,20)(11,19,17,23)(15,22,18,24)(25,28,29,36)(26,31,32,38)(27,34,35,40)(30,37,33,39)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.