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