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