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