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)(11,16,20,23)(12,22,18,13)(14,19,21,24)(25,26,31,35)(27,36,39,32)(28,29,40,33)(30,34,38,37)(1,3,5,8)(2,6,4,7)(9,11)(10,16)(12,21)(13,19)(14,18)(15,20)(17,23)(22,24)(25,27,31,39)(26,32,35,36)(28,37,40,34)(29,38,33,30)(10,17)(11,20)(12,18)(19,24)(25,28,31,40)(26,33,35,29)(27,37,39,34)(30,36,38,32)(1,4,5,2)(3,7,8,6)(9,12,15,18)(10,13,17,22)(11,21,20,14)(16,19,23,24)(25,28)(26,29)(27,37)(30,36)(31,40)(32,38)(33,35)(34,39)(9,13)(10,18)(11,19)(12,17)(14,16)(15,22)(20,24)(21,23)(25,29)(26,28)(27,38)(30,39)(31,33)(32,37)(34,36)(35,40) involution — undirected(9,14,15,21)(10,19,17,24)(11,18,20,12)(13,23,22,16)(25,30,31,38)(26,34,35,37)(27,29,39,33)(28,36,40,32)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.