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