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