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