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