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