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