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)(27,35)(28,29)(30,34)(31,33)(32,38)(36,37)(39,40) 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)(26,32)(28,39)(29,37)(30,38)(31,40)(33,36)(34,35)(9,12,15,22,14,21,13,11)(10,16,19,23,18,20,17,24)(25,28,29,26,30,33,31,34)(27,36,40,32,38,39,37,35)(2,6)(5,7)(9,13,14,15)(10,17,18,19)(11,21,22,12)(16,24,20,23)(25,29,30,31)(26,33,34,28)(27,37,38,40)(32,36,35,39)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.