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