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