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