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