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