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