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