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