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