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