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