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