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