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