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