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