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