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)(12,18,14,20)(13,28,31,39)(16,32,36,24)(17,26,38,23)(19,27,33,30)(29,34,40,35)(2,6)(3,4)(7,8)(9,11)(10,16)(12,23)(13,29)(14,26)(15,25)(17,33)(18,34)(19,38)(20,35)(21,36)(22,28)(24,30)(27,32)(31,40)(37,39) involution — undirected(2,7)(3,4)(6,8)(9,11)(10,17)(12,26)(13,24)(14,23)(15,25)(16,33)(18,22)(19,36)(20,37)(21,38)(27,40)(28,34)(29,30)(31,32)(35,39) involution — undirected(2,8)(6,7)(9,12,15,14)(10,18,21,20)(11,23,25,26)(13,27,31,30)(16,34,36,35)(17,37,38,22)(19,28,33,39)(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.