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