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