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)(11,16)(12,14)(13,27)(15,19)(17,31)(18,29)(20,24)(21,36)(22,25)(23,33)(26,40)(28,39)(30,35)(32,38)(34,37) involution — undirected(1,3,6,2)(4,8,5,7)(9,11)(10,16)(12,25)(13,28)(14,22)(15,24)(17,34)(18,33)(19,20)(21,30)(23,29)(26,32)(27,39)(31,37)(35,36)(38,40)(9,12,14,19,15,18,29,10)(11,20,23,25,24,16,22,33)(13,26,30,27,31,35,40,17)(21,36,28,39,38,32,37,34)(1,4,6,5)(2,7,3,8)(1,5,6,4)(2,7,3,8)(9,13,29,40,15,31,14,30)(10,17,18,35,19,27,12,26)(11,21,22,37,24,38,23,28)(16,32,25,39,20,36,33,34)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.