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