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