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