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